Remove furniture and other items from the carpeted area.
Pull the edges of the carpet -- on the side near the crease -- gently away from the molding and off the tack strips with your fingers. Lay the excess carpet on the molding with the carpet edges facing away from the floor.
Push the carpet toward the floor. Cut any carpet remaining on the molding from the main section of carpeting with a sharp-bladed utility knife.
Remove all broken tack strips or any strips missing gripping teeth by prying between the bottom of the strip and the surface of the sub floor with a pry bar. Cut a new length of tack strip to match each removed piece using a pair of straight-cut aviation snips. Lay the cut pieces in the space left by the damaged strips. Hit the nails -- secured in the tack strip -- toward the subfloor with a hammer to secure each strip.
Set the base of a carpet stretcher on the wall molding farthest away from the crease. Place the other end of the stretcher on the carpet near the opposite wall. Push the stretcher handle toward the floor to stretch the carpet back out. Inspect the crease. Add additional pressure with the carpet stretcher if any sign of the crease remains.
Cut the excess length from the carpet with the utility knife. Push the carpet onto the tack strips. Force the edge of the carpet under the molding with a putty knife before releasing the carpet stretcher. Move the stretcher. Repeat the carpet stretching operation until all creases are removed.