Remove the regulator handle clip using a rag as shown.

Inner handle removal/installation
Regulator handle installationMazda 6 Service Manual: Lane Departure Warning
If the system determines that the vehicle may deviate from its lane, the lane
departure warning (beep sound, rumble sound*1, or steering wheel vibration) is activated
and the direction in which the system determines that the vehicle may deviate is
indicated in the multi-information display and ...
Mazda 6 Service Manual: Head Restraints
Your vehicle is equipped with head restraints on all outboard seats and the rear
center seat. The head restraints are intended to help protect you and the passengers
from neck injury.
WARNING
Always drive with the head restraints installed when seats are being used
and make sure they are pro ...