Hm. Went to see if I have some long-forgotten account—yep! Try to deactivate account… but it’s been so long since I logged in that they won’t let me do anything until I answer a bunch of stupid questions including giving them my name.
Sigh.
[edit] it said the name would be used for “verification” (?!?!) but a fake name worked long enough to let me disable the account, anyway.