help

Turn off Find My iPhone Activation Lock (formerly: Activation Lock: Removing a device from a previous owner’s account) - https://support.apple.com/HT201441 - If an activation lock was put on a device, only the owner of the account that applied the lock can remove it.

Apple won't ask anybody, and they won't remove it unless you have the original receipt and go to a store (and even then they may only do it for the original owner).

No, the seller is required to do the following but is under no obligation if they choose to ignore what is necessary. Apple can not enforce it.

What to do before you sell or give away your iPhone, iPad, or iPod touch - Apple Support