How do I get rid of Chromium?

Chromium is rendering my computer useless. Chromium has always ran in the background, but only one instance of it and it hasn't been using too much CPU. Lately however my computer has had several instances of chromium running, always at least 3, and they're using waaaaaaay too much CPU. One is always using AT LEAST 20% and the others anywhere between 1 and 15%. So this slows down my computer quite a bit.

While just browsing the web I only really notice it on Reddit and YouTube, but that's probably because I don't really frequent any other sites.

On YouTube the site will randomly freeze while scrolling, stop loading a channel when I visit so that the "Videos", "Playlist", About," etc. tabs won't load, videos take longer to load (used to load instantly), and it takes forever (relatively) to enter fullscreen. Also, Chrome has a tendency to stop working if I try to do stuff like switch tab to pause another video while a video is loading in another tab, something that I never had problems with prior.

On reddit I just notice it by the site being slower than usual and images taking their sweet time to load.

And, as I mentiond before, if I'm trying to do something in one tab while other stuff is happening or loading in another tab(s) chrome tends to crash, something that never happened before Chromium infested my PC.

Now it's gotten to the point where I can't even play video games. And I'm not talking about trying to play graphicly demanding games like The Witcher 3 or Battlefront. I could't even play LEGO STAR WARS 2 without dipping into 5 frames per second.

I've googled around quite a bit and I haven't really found anything useful. The only information I've found is that there are other people who has the same problem as me, although on a smaller scale, and that Chromium is mostly useless and does pretty much nothing so it's fine to delete it.

However I can't seem to delete it. On all the places I've looked people have said to use Malware Bytes, ADWCleaner or CCleaner to remove it but none of those softwares has been able to find it. I haven't been able to manually delete it either.

So how do I remove it?

I'd also like to know why this happened. I assume Chromium has something to do with Google Chrome but why is it suddenly running at least 3 (usually around 5-7) instances of it and why is suddenly murdering my CPU?

I haven't installed any new programs before this happened nor have I installed any new Chrome addons. I really have no idea what might have triggeed this.

I have an Intel Core i5 3570K CPU and 16 gigs of RAM.