begin tran
create table #UserList (fldUserName nvarchar(max) collate SQL_Latin1_General_CP1_CI_AS)
insert into #UserList (fldUserName) values
DELETE from tblPERMS_Incidents where Username_Incidents collate SQL_Latin1_General_CP1_CI_AS in (select fldUserName from #UserList)
drop table #UserList
rollback tran
fldUserName nvarchar(max)2. Your INSERT into #UserList query is missing the values.. Kindly clarify whether you meant to insert only 999 records to this table.
insert into #UserList (fldUserName) values
insert into #UserList (fldUserName) values
('asdfsa')
('gwerq') --The manual insert errors.
etc
DELETE from tblPERMS_Incidents where Username_Incidents collate SQL_Latin1_General_CP1_CI_AS in (select fldUserName from #UserList)