If there are publicly-available records connecting you to a phone number, lack of immediate access shouldn't be a disqualifier.
Like what? My guess is that the records must not only be available, but also tamper-proof, and from the top of my head I don't know what it could be.
So, if there are publicly-available records incorrectly connecting you to a phone number, then you should be able to delete accounts under from the rightful owners?
If there are publicly-available records that link you to a phone number because you used to use it, then you should be able to delete the current account which is used by the current owner of it?