In 2014 I went to a javascript meetup with an idea to create a neat UI for gmail called PMail I never got it to work because I didn't understand oAuth all that well. I tried all night and couldn't find any help, so I demo'd the UI with some fake data and life went on. It was a fun experience regardless. Now ten years later personal data has become what it has become, so this app exists to delete all emails from gmail, in bulk.
You can use it too... when it's ready.
Also I want to thank @TylersTech2020 for the starter code.