To move the couch it maybe worth considering removing the window if you are on a ground floor, they are often wider than doors. I am sure however that it will be perfectly safe to remove the door frame as long as you put it back carefully in the same place.
the best way would be to get a friend to help stand the couch upright then turn the back of the couch into the gap tilt if the couch is to long this should give you a good angle to get the couch in also take any cushions of arms where possible