how do i permanently turn off the front collision detection system on my 2015 gmc 1500 sierra? I have a grill guard and it constantly goes off

As for the safety features, under the Collision/Detection Systems section under Settings via the radio screen ... You should be able to turn off the auto collision avoidance.

i have done this, but it resets everytime i turn start the truck. is there a way to permanently turn it off? thanks for the help

if it resets automatically, then it sounds like only a dealer can disable it. I'm not sure if they can or if its a legal/safety issue. Just explain your situation to them on the phone. You may also have a fuse for or a connector going to the collision detection, maybe you can find/disable it yourself? It probably will set off an error on your dash but would avoid a dealer trip