I am not able to compact user database (.nsf)files after archiving from user end. After archiving there are only few mails in the Inbox, but the .nsf file size remains same.
Check the document count on the database properties tab, not the inbox count. Likely, the messages are in the trash folder and thus are still part of the file. Emptying the trash prior to the compact would help in that case. You might also want to look at the Admin help for the switches available to you when running the compact tool. I like to run user mailfile compacts with -c -i -L , as it seems to best solve problems users have when over quota.