5 pin to 3 without losing functionality

Hi all,

I’m working on a project that uses a motor throttle and speed controller. There’s only one problem: the speed controller has three pins (see pictures for help) whilst the throttle has five. There is a red black and green wire for the throttle and then two more, presumably for the “on off” function.

I would really like to connect the throttle and speed controller up but don’t want to lose the “on off” functionality of the throttle. Is this possible? If so, how do you go about doing it?

Thanks!