So I downloaded a few fonts from this website and I want to uninstall some of them but when I try to delete them under my Control Panel>Appearance & Personalization>Fonts it says that the fonts cannot be deleted because it's still in use. None of my files are using that font anymore. Can anyone help me with this? I have an ASUS Windows 8 touchscreen laptop, if that helps.

photoshop, word, illustrator, or whatever software you were using the fonts in, might still be open.
If not, restart your computer.