Temp files and Windows Picture and Fax Viewer

Alright, I'm not all that computer savvy so hopefully this makes sense, narrative is the only way I know to describe...lol....and I'm probably not calling something the right deal, but whatever

One day I was viewing a picture from an email on the Windows Picture and Fax Viewer and hit the back button and noticed tons of temp images, thumbnails, etc. You can manually delete things if you want, but that takes forever (don't ask why I need to delete..lol) and the images rotate kinda randomly.

How do you get rid of temp files, thumbnails etc. that go into unknown folders somewhere on the PC...is there any way? Hopefully easy, I'm computer illiterate