You may follow below steps to clear the tmp folder contents from your end.
**** Any files removed can not be replaced***
1. Login to Cpanel.
2. Click on FileManager under Files.
3. Select "Home Directory" as "File Manager Directory" and click on Go.
4. This will show the home directories including tmp directory.
5. Please do not delete tmp directory. You may delete the files inside, which will cause the stats generated for that domain.