Quitclaim

A release or relinquishment of a claim; a deed of release; an instrument by which some right, title, interest, or claim, which one person has, or is supposed to have, in or to an estate held by himself or another, is released or relinquished, the grantor generally covenanting only against persons who claim under himself.(Law)

To release or relinquish a claim to; to release a claim to by deed, without covenants of warranty against adverse and paramount titles.(Law)