The easiest way to do this is just go to the folder where the databases are located and highlight it and delete. Gone. Now remember, if the database is connected to another one, you will receive errors when opening that other data base. So you might consider creating a folder named “Deleted DBs” and just move them into this folder until you are sure that you really want it gone. Just a safety precaution.
For more info See this: http://office.microsoft.com/en-in/access-help/delete-an-access-file-HP005188371.aspx