@isTest
public class RemovePermissionSetsTest {
    static testmethod void createTestData(){
        Test.startTest();
        List<User> usersList = new List<User>();
        User user = new User(
            ProfileId = [SELECT Id FROM Profile WHERE Name = 'System Administrator'].Id,
            isActive = true,
            LastName = 'last',
            Email = 'test@test.com',
            Username = 'test@test.com' + System.currentTimeMillis(),
            CompanyName = 'TEST',
            Title = 'title',
            Alias = 'alias',
            TimeZoneSidKey = 'America/Los_Angeles',
            EmailEncodingKey = 'UTF-8',
            LanguageLocaleKey = 'en_US',
            LocaleSidKey = 'en_US');
        usersList.add(user);
        insert usersList;
        System.debug('users: '+usersList[0].Id);
        
            PermissionSetAssignment permissionSetAssignment = new PermissionSetAssignment();
            permissionSetAssignment.PermissionSetId = '0PS6g000004ULGa';
            permissionSetAssignment.AssigneeId = usersList[0].Id;
            insert permissionSetAssignment;
        System.debug('permissionSetAssignment: '+permissionSetAssignment.Id);
        
        usersList[0].isActive=false;
        update usersList[0];
        System.debug('users update: '+usersList[0].Id);
       
   
        Test.stopTest();
    }
}