iCloud seriously is the stupidest thing

My computer hard drive, which is way too small for this machine, keeps getting full and a large reason for this is that the iCloud (that storage that's supposed to be online in the cloud) takes up a big chunk of my hard drive space. I discovered this previously and stopped paying for the extra space and even turned off the iCloud and it just kept loading things into it!

Then, on top of that, I have these other chunks of data that I can't even get into to access and have no way of sorting and cleaning. I'm to the point where I have gotten so disgusted with Apple and these antics that I'm just ready to go PC. Please tell me there's some way to actually clean this hard drive and run my programs or I swear I'm done with Apple.