Yup, file the nub off the key to make it removable when in the "ignition" position.

I did one better and mounted a toggle switch in-line on the red wire going into the ignition switch. Now the switch remains in the "ignition" position and the key is no longer used. I just flip the toggle that I mounted above the horn, hit the start button and ride away. The ground down key and fob never leave my pocket.

 

I did one better I didn't file the key at all so it saved time. I just left the key in the ignition and rode off with the fob in my pocket. Simplest solution

 

I think Willie G has a rule against that. Sorry.

 

I use a round dot of Velcro to keep it secured to the frame.