If it the Windows software distribution folder, check for updates again. It should recreate it if memory serves. At least that's what I seem to remember when I used to do cleanups and would have to do things like that to make updates work again. However, don't randomly delete things you don't know. At least use a program like CCleaner to free up space.
However, ssds are relatively cheap. You can get a 500gb for about 50 to 60 dollars these days