Thanks for those links, they are definitely a good approach.

Here is a piece of code from someone that was working in my company. We have no developers right now and my level on APEX is not even close to this. The problem is that this code is not working for some reason and I can't figure out why. I was thinking on writing something my self but I still need to understand better apex before building something that will delete our accounts in case they are part of a  specify criteria. 

Can someone let me know if there is something wrong on this script?

Thanks in advance!

public class Account_To_Be_Deleted_Methods {

    Id accId;
    Account acc;
    List<Contact> con;
    List<Id> contactIds = new List<Id>();
    List<Id> whatIds = new List<Id>();
    User hiddenOwner;
    List<Opportunity> opp, openOpps;
    List<Task> tsk, openTsks;
    List<Event> evt, openEvts;
  boolean hasOpenOpps, hasOpenTsks, hasOpenEvts;

    public Account_To_Be_Deleted_Methods(ApexPages.StandardController controller) {
        accId = ApexPages.currentPage().getParameters().get('id').substring(0, 15);
        acc = [SELECT Id, OwnerId, Name, Account_Status__c FROM Account WHERE Id = :accId];
        con = [SELECT Id, OwnerId FROM Contact WHERE AccountId = :accId];
        for (Contact c : con) {
          contactIds.add(c.Id);
        }
        hiddenOwner = [SELECT Id FROM User WHERE Name = 'Hidden Accounts' or Name = 'Accounts Hidden' LIMIT 1];
        opp = [SELECT Id, Name, StageName, Amount, CloseDate, AccountId, IsClosed FROM Opportunity WHERE AccountId = :accId];
        whatIds.add(accId);
        for (Opportunity o : opp) {
          whatIds.add(o.Id);
        }
        tsk = [SELECT Id, Subject, ActivityDate, Status, WhatId, WhoId, IsClosed FROM Task WHERE WhatId IN :whatIds OR WhoId IN :contactIds]; 
        evt = [SELECT Id, Subject, WhatId, WhoId, StartDateTime, EndDateTime FROM Event WHERE WhatId IN :whatIds OR WhoId IN :contactIds];
    }
  
  public PageReference deleteAccount() {
    
    if ((UserInfo.getUserId() == acc.OwnerId || UserInfo.getUserRoleId().substring(0, 15) == '00E30000000oNdM' || UserInfo.getUserId().substring(0,15) == '00580000003Ll8Y' || UserInfo.getUserId().substring(0,15) == '00580000003LkKd') && opp.isEmpty() && tsk.isEmpty() && evt.isEmpty()) {
          Database.DeleteResult dr = Database.delete(acc);
    }
    else {
      hasOpenOpps = checkOpenOpportunities();
      hasOpenTsks = checkOpenTasks();
      hasOpenEvts = checkOpenEvents();

      // If it is not the owner of the Account or a System Admin, do not allow the Account Deletion to occur
      // Also set the boolean 'has' variables to false . This prevents the related list vies appearing on the page
      if (UserInfo.getUserId() != acc.OwnerId && UserInfo.getUserRoleId().subString(0, 15) != '00E30000000oNdM' && UserInfo.getUserId().substring(0, 15) != '00580000003Ll8Y' && UserInfo.getUserId().substring(0, 15) != '00580000003LkKd') {
        Apexpages.addMessage(new ApexPages.Message(ApexPages.Severity.FATAL, 'Your are not the owner of the Account ' + acc.Name + '. Only the Account Owner can delete the Account.'));
        hasOpenOpps = false;
        hasOpenTsks = false;
        hasOpenEvts = false;
      }
      else {
        if (hasOpenOpps || hasOpenTsks || hasOpenEvts) {
                 if (hasOpenOpps) {
                   Apexpages.addMessage(new ApexPages.Message(ApexPages.Severity.FATAL, 'Account ' + acc.Name + ' contains an open Opportunity'));
                 }
                 if (hasOpenTsks) {
                   Apexpages.addMessage(new ApexPages.Message(ApexPages.Severity.FATAL, 'Account ' + acc.Name + ' (or an associated Contact) contains an incompleted Task'));
                 }
                 if (hasOpenEvts) {
                   Apexpages.addMessage(new ApexPages.Message(ApexPages.Severity.FATAL, 'Account ' + acc.Name + ' (or an associated Contact) contains an open Event'));
                }
        }
        else {
          acc.OwnerId = hiddenOwner.Id;
          acc.Account_Status__c = 'Deactivated';
          acc.To_Be_Deleted__c = true;
          acc.RecordTypeId = '012300000001X5I';
          update(acc);
          if (!con.isEmpty()) {
            for (Contact c : con) {
              c.OwnerId = hiddenOwner.Id;
              c.RecordTypeId = '012300000001X5S';
            }
            update(con);
          }
        }
      }
    }
        if (!Apexpages.getMessages().isEmpty()) {
          return null;
        }
        PageReference pageRef = new PageReference('/001/o');
        pageRef.setRedirect(true);
        return pageRef;
  }
  
  public boolean checkOpenOpportunities() {

        // Place any open Opportunities into the openOpps List.
        // Return true if any open Opportunities are found. Otherwise return false.
        openOpps = new List<Opportunity>();       
         for (Opportunity o : opp) {
             if (!o.IsClosed) {
               openOpps.add(o);
             }
        }
        if (openOpps.isEmpty()) {
          return false;
        }
        return true;
  }
  
  public boolean checkOpenTasks() {
        // Place any open Tasks into the openTsks List.
        // Return true if any open Tasks are found. Otherwise return false.    
    openTsks = new List<Task>();
    for (Task t : tsk) {
      if (!t.IsClosed) {
        openTsks.add(t);
      }
    }
    if (openTsks.isEmpty()) {
      return false;
    }
    return true;
  }
  
  public boolean checkOpenEvents() {
        // Place any open Events into the openOpps List.
        // Return true if any open Events are found. Otherwise return false.
        openEvts = new List<Event>();    
    for (Event e : evt) {
      if (e.EndDateTime > Datetime.now()) {
        openEvts.add(e);
      }
    }
    if (openEvts.isEmpty()) {
      return false;
    }
    return true;
  }
  
  public String getName() {
    return acc.Name;
  }
  
  public List<Opportunity> getOpenOpps() {
    return openOpps;
  }
  
  public List<Task> getOpenTsks() {
    return openTsks;
  }

  public List<Event> getOpenEvts() {
    return openEvts;
  }
  
  public boolean getHasOpenOpps() {
    return hasOpenOpps;
  }
  
  public boolean getHasOpenTasks() {
    return hasOpenTsks;
  }
  
  public boolean getHasOpenEvents() {
    return hasOpenEvts;
  }
}