Did you use the user-level security wizard? If so, it put a shortcut to the
secured database on your desktop. In order to be able to login with one of
the user name/password combos you set up, you must use this shortcut.

If you used the user-level security wizard and have decided you no longer
want security, first MAKE SURE YOU STILL HAVE THE .BAK FILE IT CREATED FOR
YOU. Once you are sure you do, rename the .bak file to a .mdb file. After
this, open it and make sure everytihng is okay. Make sure no data was lost,
corrupted, etc. Make sure there is nothing in the secured version that the
.bak file does not have unless it is something you can easily recover or
recreate.

Once you are sure the .bak file will suffice, and you've renamed it a .mdb
file, delete all of the security files involved (the secured version of the
database, the workgroup file, which is probably called "Secured," etc.). Be
aware that once you have premanently (in other words, also delete them from
the recycle bin if they go there) deleted them, you cannot get them back.
You'd have to redo the security setup if you change your mind again.