Since only the person who created a data grid can remove it, you must add the person back to the user list and then log in as them and then delete it.
  1. Tools > System Utilities > Establish System Users.
  2. Click New and add the user name.  No password is needed. Save.
  3. Login to FIMS with the restored user name.
  4. Find and delete the various data grids you want removed.
  5. Return to Tools > System Utilities > Establish System Users.
  6. Remove the user.