i want to reinstall because i did something wrong and a bunch of space is taken up by something that i can't deleteTell me why you want to reinstall, there is no reason to reinstall, none.
It's not the mandatory 2 year Windows reinstall because it will get slow.
OS X/macOS does not slow down, and if it does there are easier ways to solve it without a reinstall.
There's just 1 or 2 reasons to reinstall, 1 of them is if you F...ked up your disk by fiddling with permission, second is if the filesystem is so corrupt that even Diskwarrior can't repair it, and that is very..VERY rare.