Pull the carpet away from the corner wall that is closest to the creases with pliers. Grasp the carpet where it meets the wall to lift the carpet away from the tack strips underneath the carpet.
Adjust the depth of the teeth that extend from the bottom of a carpet kicker tool to match the depth of the carpet. Turn the knob on the tool to adjust the teeth. Refer to the portion of carpet pulled off the tack strips to determine the depth of the carpet. The goal is to allow the teeth of the kicker tool to grasp the carpet without penetrating the backing underneath the carpet.
Position the knee kicker behind the creases and gently bump the kicker tool with the top of your knee to straighten the crease.
Work toward the corner of the wall with the kicker tool until the kicker tool is about two inches away from the wall.
Thrust your knee into the kicker tool one final time to tighten the carpet against the wall, then gently tap the carpet onto the tack strips with a hammer.
Tuck the carpet against the wall with a four inch wallboard knife and trim the excess carpet material with a utility knife.