For the headrail you can use a hacksaw or a pair of tin snips to cut it. Don't worry too much about the looks of the headrail cuts because you won’t see them once they are placed in the box type brackets.
1. Measure in the distance you would like to cut and mark a line. You can cut an even amount off of each side of the headrail or if it is a small amount, just cut it off of the lift cord side of the headrail.
2. Remove the end stiffener from the headrail.
3. With the tin snips or hacksaw, carefully cut the headrail along the mark you made. As you cut the headrail you may want to bend the cut portion out of the way with pliers or a screw driver.
4. Bend the ends of the headrail back out into position with pliers or a screw driver.
5. Replace the end stiffener back into the headrail.