There is not a watertight solution to do so. Access security is easily compromised. The tightest solution to shield your data is to use Access built-in UAC (User Account Control).
In a nutshell:
Create a brandnew workgroup file and use it to open your database. Now set the Admin password for the backend. Do the same for the frontend. Strip the Admin group from all its privileges. Create your own group and add users to them. Grant permissions to the group.
Don't loose the unique string you used to create the workgroup file.
Enjoy!