it's actually sort of hard to get gmail to delete a decade's worth of email. at least google takeout makes it easy to get the whole thing as mbox though
@doenietzomoeilijk it's just slow, but selecting all of the messages and moving to trash works. then you have to empty the trash. each step takes a while
@sneak No, it doesn't make it easy at all. You can launch the archival process, but it doesn't let you actually download anything until you enter a phone number so it can send you a confirmation code. With no phone number tied to the account I can't imagine how this improves security, you can enter any phone number. I've ended up downloading everything with fetchmail and deleted the account afterwards. Oddly enough no confirmation is required in this case.
@sneak add a rule to delete messages to you, apply to inbox? Just guessing, but that might work.