unhelmet

Etymology

From un- + helmet.

verb

To remove the helmet from.“In spite of all that Durward could say of the slightness of his hurt, he was compelled to dismount, and to seat himself on a bank, and unhelmet himself”
To take off a helmet“Due to security protocols—ones I had devised—I had to unhelmet at the front gate and a guard with a slavering dog met me in the circular drive.”