Records Not Completley Deleted after Deleting Changelog Data (Requests) ???

Hello Experts,

I wounder if you guys could help me in understanding deleting ODS Changelog Tables...

After knowing that few of our changelog tables in Production occupied large memory space I have deleted the Change Log request from ODS Manage Screen. Even After deleting all request some tables still occupied considarable memory space.

Please give me scenarios where it could happen and how to delete them and any impacts after deleting them.

As usual I will Assign points for proper response.

Many Thanks,

Ravi Kumar.