To shorten an artificial Christmas tree, follow these steps: 1. First, make sure that the tree is unplugged and no longer connected to any power source. 2. Next, locate the metal screws or pins that hold the sections of the tree together. 3. Unscrew or loosen these screws to release the tension between the sections of the tree. 4. Once the screws or pins are loosened, you should be able to pull the sections apart. 5. Now, start shortening the tree by removing some of the bottom sections.