There are several ways to keep a cat away from the Christmas tree. One way is to use a motion-activated air blaster or a spray bottle filled with water. When the cat approaches the tree, you can spray it or use the air blaster to scare it away. Another way is to provide the cat with its own special place away from the tree, such as a cat perch or a cozy bed. This will give the cat a place to relax and play without being tempted to climb the tree. Additionally, you can use a vertical scratching post near the tree to redirect the cat's attention and discourage it from climbing the tree.