Turn the couch upside down so its legs stick in the air. Unscrew the legs and sit them aside. Pull out each of the staples underneath the couch using a staple puller. Pull back the couch fabric, ripping any seams with a seam ripper if necessary. Continue to remove the fabric until it is completely off of the couch, cutting it with scissors if necessary for complete removal.
Spread the removed fabric out and measure its dimensions. Cut out a piece of new fabric that is at least 1 yard larger than the old fabric. Spread the new fabric over the couch.
Tuck the new fabric in all around the couch seat. Push it all the way to the wooden frame and staple it tightly in place against the frame and out of sight using a carpentry stapler. Staple the fabric in the back crack of the seat and both side cracks between the arm rests. Stretch the fabric down over the front of the couch.
Stretch the fabric up and over both arms and over the backrest of the couch. Staple it discretely if needed to keep it tight, but ideally just pull it underneath the couch. Flip the couch upside down and stretch the fabric tightly on all four sides.
Staple the tightly stretched fabric to the underside of the couch, about four inches from the outside edge. Space the staples every four inches. Cut off any excess fabric using scissors.