How is it done? It has been broken and the scooter has an E2 error. The throttle assembly appears to be modular. I see...

Remove the handle bar extension and grip by unscrewing it clockwise. Extra effort may be needed. Using a 3/32" hex key allen wrench, loosen the inset screw found on the underside of the throttle body shroud. Slide the throttle assembly off the end of the handle bar. Using a sharp knife, carefully cut through the shrink tubing protecting the wire lead terminal connections. Uncouple the terminals. Voilà!