Detaching a garage door from a screw drive opener system for screw drive models the shuttle release lever will be engaged and in the up position see image 1 below.
Overhead garage door engage and disengage.
All you have to do to disengage it is just pull down on it and pull it toward the house and that will keep it keep the spring on the on the trolley up there extended so that it does not hang up on the trolley and then you ll be able to lift your door from the handle that should be located on one of the lower sections and you can pick your door up.
To disengage you ll pull the emergency release cord down which will release your garage door from the opener system.
It might be necessary to pull the door closed slightly to fully engage the trolley.
Make sure the carriage unit is nearest to the garage door.
Pull the release rope and push the door all the way up until you hear a click.
The opener trolley will engage the carriage once it comes to the full open position.