Make sure the back of the futon frame is at least two feet away from the wall.
Stand at one end of the futon frame. It will be easier if the seat of the futon is on your right if you are right-handed.
Grab the top corner of the back of the futon with one hand and the front corner of the seat of the futon with your other hand.
Lift both corners and while lifting pull the seat out and up. As the seat slides forward the the angle at the bottom will disengage from the frame and you can then gently lower the back and pull the seat forward until the futon is flat.