Glider configurations and motor control


I recently tried out the arduplane program on one of my gliders (similar to comon easystar, I have the Sky Surfer from Siva). I was quite pleased to see the glider operate autonomously but I still need to do some ajustements. The main problem that I encounter is that the motor keeps running, at different speeds of course, but I want it to turn off in order to allow the plane to glide.
My question is the following : what are the parameters that I should be working on in order to program a gliding phase. I am using the matekh743 flight controller with only a GPS connected to it. I do not have an airspeed sensor for now. I would rather glide without the airspeed sensor (for cost purpose) if not necessary.
I also wanted to ask you if there are other parameters that I should be aware of in order to configure correctly an autonomous glider.

Thank you for your support