Kill switch for a Mini Pro with handlebars

[pop80 2]

Hey all, 

I am new here, this is my first post.

I have a MiniPro and a Ninebot ES1 

I have just fitted handlebars to my MiniPro, and now obviously I have some run away and it will not balance. 

So my question is, has anyone else fitted a kill switch? 

So basically I could wear a wrist band with a cable attached, if I come off then it pulls the power to the motor and shuts the Ninebot down immediately, avoiding an accident. 

Thanks in advance