Ask a neighbor, family member or friend to assist you in removing the door header.
Place a drop cloth in the doorway to catch any small dirt and dust particles as well as any screws that come loose and fall to the floor before you can grasp them.
Put on eye protection, a dust mask and work gloves.
Remove the side jambs starting with one side. Unfasten the retaining screws drilled through the side jamb into the brick wall with a screw gun. Then, take the retaining screws out of the other jamb using the screw gun.
Attempt to pull the jambs out by hand. If the jambs will not come free from the wall by hand, gently pry them away using a pry bar. Set the jambs aside so they do not become a tripping hazard.
Unfasten the retaining screws driven through the door header into the brick opening. Do not stand directly under the header as you remove the screws, as there is a possibility it will come loose and fall.
Try to pull the door header away from the top of the rough opening by hand, standing outside the opening. Use a pry bar if the header will not come down after pulling by hand.