Post-GDPR both companies will be required to. GDPR entitles European citizens to go dynamite fishing by sending companies requests to delete any data that is identifiable as being associated with that citizen.

You have to identify yourself to make the request, but the process should be self healing because they are then required to also delete the PII in your request to delete your PII (unless it's required for regulatory reasons, but this applies more to banks than google or facebook).

And before that we were already entitled to request that data, which FB "respectfully" dragged their heels over when people actually tried to use that right.