How clear list of waypoints from AI Aircraft?

I can set a list of waypoints to an AI aircraft - it successfully flys the route.
But I want to clear the set of waypoints from the AI aircraft once the last waypoint is reached.
(The aircraft is on the ground at this point with 0 height and 0 airspeed).
Any pointers ?

Someone else had a problem with updating the waypoint list. Maybe the workaround here works for “clearing” (which is an “update” really) as well?