Over time you may accumulate deleted emails and may want to delete them. Although emails automatically get permanently deleted in the trash section (where deleted emails are stored) in thirty days, you may want to delete them.
1. Go to https://mail.google.com/mail/
2. Go to "Search all conversations" at the top left-center of the tab
3. Type in:trash
4. Once in the trash section, you can delete certain emails, recover emails, and empty the entire trash by using the "empty trash now" button. Just to be sure - emails cannot be recovered when deleted in the trash section of Gmail.