Even if you have never been registered on Facebook etc.: Facebook knows your mobile number and mail address because other people have already uploaded them.
You can delete your phone number/mail address from meta's database via the following website:
@fomm @jurjen_heeck @briankrebs is there one for LinkedIn? I purposely deleted my original LinkedIn account to get a fresh restart with no connections. When I created a new LinkedIn account and instructed it not to be found via email or phone, I was still located by people who had my contact info.