mech29 told us that he gets an error messages when he tries to delete users.
So I fear, that these accounts have been used.
And that makes life a little bit more complicated.

At some point, your going to have 'dead' records in your system. Looks like these are going to be some of them. Just disable the users or mark the employees out of service and move on. If no one can log in using the user ids, and people can see the employees in the LOVs, then no one's the wiser. Not everything is worth trying to delete.

If you have the user associated to any record in 7i you will not be able to remove the user. If you used the user for a work order that is history, if they are associated to a craft or trade that also links them to a history record. Do you have Audit setup. If so and you have history you will never be able to remove the user