Hi Feng,
I am Dave, I will help you with this.
1
If this happens when you are programming, then Defender may be scanning your newly created executables, and that may be causing the high CPU usage, because it would not recognize your code.
The best option when programming in Windows is to create a parent folder for all your programming projects, then add that folder to the exclusion list in Defender.
2
Otherwise, defender may be caught in a loop, the best option is to open Defender, then select the option to perform an offline scan, your PC will reboot to perform that scan, that usually takes Defender out of the loop.
3
If you still want to remove Defender, the only real way to do that is to install a 3rdp arty anti-virus, because your PC needs to be protected, and 3rd party anti-virus suites will disable Defender automatically.