How do you remove the Start button?

You have to pull the radio cover off to push in on both sides of the starter switch if you want to remove it

sent from the Bader Badger, FAST red slingshot

Yup. Was just reading something on TDS about it - not my photo

sent from the Bader Badger, FAST red slingshot

I'm not near my Slingshot at the moment, so this is from memory. Check this thread on disassembling the dash - Insulating the Infotainment Cubby Area From Engine Compartment Heat. Taking the dash apart gives the easiest access, but you should also be able to access the switch thru the Infotainment cubby opening.
I just checked my pdf instructions and the switch isn't pictured very well. Here is a picture from the parts diagrams -

The switch should pop out just like the other switches, but be careful as it costs around $50 to replace it! In my opinion, removing the dash and disconnecting the wires should make it easier to access the starter switch for removal/modification, but it can be accessed from the cockpit thru the cubby opening.

If I recall correctly from when I took mine off, it might have those push fasteners... Maybe 2? 1 on each side.. Or that may have been the console... Can't remember!

As I mention in my pdf on Insulating the Cubby Area, there are 2 push pins securing the dash that are located immediately under the 2 inner switch positions. after removing the 8 T40 fasteners, removing these 2 push pins and the wires connecting the switches will allow you to remove the dash for easy access to the starter switch.