To delete a database, you should be in the Ability Database window and make sure that the database you want to delete is closed:
Select Open Database from the File menu. The "Open existing database" window is displayed.
Locate the database to be deleted and right click on it.
Select Delete from the displayed menu. You will be asked if you are sure that you want to delete this database. Click on Yes and the database will be deleted.
If the database is open, an error message will be displayed and you will not be allowed to go ahead with the deletion (see Closing a database).