For EU citizens, they have to legally abide by deletion and correction requests. However, if you can’t prove you own the account (through your email address for instance), they can demand you show proof that you say who you are. If your name/DoB/picture doesn’t match, they can even decide you’re someone trying to do a malicious account takeover and ignore your requests. Fake data requests are easy to send and hard to catch without some strong proof of identification. Even knowing the account password may mean nothing if that password has been leaked before at some point.