How to remove MRT (Malware Removal Tool)?
Removing Apple's Malware Removal Tool is not a good idea, so it's better to figure out why it's running high.
Also, 100% is a per-core figure, so on quad-core i7, you can use up to 800% CPU. Various OS processes, like Spotlight, will use similar levels of CPU for short periods.
MRT may use significant CPU for a short time while it does its job: downloading malware lists from Apple, and then checking/removing anything on that list.
If you have got a 'runaway' MRT process, then that might indicate that it is trying (but not succeeding) to remove some malware. You could try using MalwareBytes to check and remove anything on your disk, as suggested on the other thread.
At worst,  I would just recommend restarting, rather than disabling SIP and killing MRT, both of which severely reduce the security of your Mac -- particularly if malware is already on board.