Step 1: Install Reddit Enhancement Suite extension in your Chromium based browser. (https://redditenhancementsuite.com/)
Step 2: Install the Nuke Reddit History extension in your Chromium based browser. (https://chrome.google.com/webstore/detail/nuke-reddit-history/aclagjkmidmkcdhkhlicmgkgmpgccaod)
Step 3: Log-in to your Reddit account.
Step 4: Use the Nuke Reddit History extension button to nuke your comment and submissions! (Don't forget to do BOTH!)
Step 5: Open the "Preferences" page of Reddit, click on the "Deactivate" tab, then enter a loving message for our best friend Spez to read. He reads all the mail he gets. Then verify you want to deactivate your account by re-entering your login info and pressing that beautiful button!
Step 6: Uninstall those nasty gross Reddit related Extensions from your Chromium based browser.
Deport Reddit From Your Life for a better, beautiful tomorrow!