MS Access is also a flat file. Every time you open a file a session is openned in computer management session folder. So, there is a way to kill that session... you must have the rights to the machine it is located/running.
Here are the steps...
control panel ---> computer management ----> shared folders ----> Sessions -> This is where you should be able to see who is using the file and be able to terminate the session here as well.
Thank you... Hope this helps.
Koncentrix