The only protection against this is to first anonymize your account data, e.g. by entering bogus or empty detail information. Maybe even change your email address to a temporary throwaway address, in case it is needed to complete your account "deletion".

Of course, they could have saved the previous versions of all profiles. But at least you're making it harder for them to check which version was the "correct" one (i.e. the one that has any value on market of personal profiles for spammers, marketing, etc.)