Close the screen door and the steps should retract. Then reach through (Use a wand if you have to) to flip the OFF switch.
Alternate.. IF they are Kwike steps.
Close the door, "Block" the steps so they can not come out (This will not harm them) Open door flip switch close door.
Now remove the block.
Kwike steps do not use a sensor switch, in fact unless you add one they have no sensor swiches (mine has one) what turns off the motor is the current surge when the steps hit the stop. Or your foot, Or the curb, Or your leg, or a block of wood with your foot behind it. or.. Well you get the idea.
The sensor I added (A common automotive door switch) Activates a light on the dash when the ignition is live and the steps are extended.