[SOLVED] windows malicious software removal tool

Can somebody please explain why I keep getting windows updates for this program. I don't actually think i have it because i cant find it anywhere so why do i get the updates.
My pc's are custom built and only came with the windows operating system , i have the discs as well , the op system was the only software installed , no bloatware etc.
On previous shop bought ready built pc's i have used the tool as a separate program but as i say , as far as i know i dont have on these machines.
 
Solution
it gets updated every cumulative update, thats why. It is run on the day you get the update. Microsoft install it.

Its part of windows 10