When a magazine empties, the follower BY DESIGN pushes up on the slide lock lever to lock the slide back. It's difficult to overcome the slide lock spring AND the much stronger magazine spring. Remove the empty mag or use a loaded one and the slide release is easy to press down again, by design.
I always rotate and wiggle the barrel to one side on the .45's when removing it from the slide... just before it's all of the way to the rear.
If you didn't get a manual, they are available for download at https://www.kahr.com/brochures-manuals/
USAF Retired '88, NRA Life Member. Wife USAF Retired '96
Avatar: Wynn re-enlists his wife Desiree, circa 1988 Loring AFB, ME. 42nd BMW, Heavy (SAC) B-52G's
Frédéric Bastiat’s essay, The Law: http://mises.org/books/thelaw.pdf
Thomas Jefferson said
“A government big enough to give you everything you want, is strong enough to take everything you have.”
and
"Peace is that brief glorious moment in history when everybody stands around reloading".