I want to remove last 3 digits , characters in account name.

trigger opptyShareTrig on Opportunity (after insert) {
      List<OpportunityShare> share=new List<OpportunityShare>();
      User u=[select id from User where alias='knair'];
      for(Opportunity op:Trigger.New){
            if(op.stageName=='Closed Won'){
                        OpportunityShare os=new OpportunityShare();
                        os.OpportunityId=op.id;
                        os.UserOrGroupId=u.id;
                        os.OpportunityAccessLevel='Edit';
                        os.RowCause='Manual';
                        share.add(os);
            }
      }
    insert share;
  }


Getting Error

I have two different custom objects "Speaker__C" and "Session__c" both having "city__c" picklist field.
If I update City value on one object same should be populated on other object.
Both picklist have same values.

I have two different custom objects "Speaker__C" and "Session__c" both having "city__c" picklist field.
If I update City value on one object same should be populated on other object.
Both picklist have same values.