Firstly, I'd try to not run tests on true production databases if possible, but I know this cannot always be avoided.
In my tests of this type, I ensure the database is as expected with a range of simple AddEntry, DeleteEntry, AssertEntry and AssertEntryCount routines that either insert, delete, assert the content of, or assert the expected count of rows in tables with specified fields and values.
These have a TableName parameter and then a ParamArray parameter called ColumnsAndValuesAndOptionalConnectString (as well as a couple of straight SQL query overloads) that expects field names, then the same number of values and finally an optional connection string.
In your case, I'd have one (or as few as possible) test that creates a new user and if it succeeds the cleanup does actually drop the user created.
The rest should refer to a single (or again as few as possible) "Integration Testing" user that is normally marked as deleted, but that user is undeleted while tests are performed upon it.