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
@sneak add a rule to delete messages to you, apply to inbox? Just guessing, but that might work.
@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