A headrest lock guide assembly for removably securing a headrest assembly to a vehicle seat can include a lock housing configured to house a headrest post extending through the lock housing, a lock slidably located within the lock housing, and a tool passageway extending through the housing. The lock can be slid against a spring force between a locked and unlocked position by inserting a tool through the tool passageway in the lock housing. A lock housing cover can be provided that is non-movably secured to the lock housing and can include a cover abutment surface adjacent to and blocking a lock body opening in the housing. The lock can include a lock abutment surface and a post engagement member configured and dimensioned to selectively engage a portion of the headrest assembly to lock the portion of the headrest assembly within the lock guide. The lock is movable within the lock cavity between a locked position in which the post engagement member extends over a portion of a through bore and the lock abutment surface contacts the cover abutment surface, and an unlocked position in which the post engagement member is located outside the perimeter of the through bore in the hollow post stem and the lock abutment surface is spaced from the cover abutment surface. A spring member can bias the lock into the locked position.