MS Access doesn't free up space used by records even after they are deleted. You can free the space manually when you need to or automatically each time you close the application.
To do it manually, use the Compact and Repair utility:
Backup your database, as there is a bug in Access 2007 that may delete your database
during the compacting procedure.
If you are compacting a multiuser (shared) database that is
located on a server or shared folder, make sure that no one else has it
On the Tools menu, point to Database Utilities, and then click
Compact and Repair Database.
Open the database that you want MS Access to compact
On the Tools menu, click Options, and then choose the General
Select the Compact On Close check box.
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