Hold the bottom of the fan with both hands, and press the middle part of the fan with two thumbs at the same time to push it out. Don't push the fan blade, the closer it is, the better, avoid breaking the fan blade, and don't be afraid to break the fan blade with a little force. It will naturally come out when the force is applied. Start to disassemble the fan: Never push the fan blades, the farther in, the better, and avoid folding the fan:
Remove and clean the shaft sleeve, which is the chief culprit of the loud sound of CPU fan. When removing the shaft sleeve, gently remove the plastic plug at the top of the shaft with a small flat screwdriver, and the shaft sleeve can be successfully removed from the shaft.