How does one go about removing a mod, simply delete the files or is it more complex?
I take it you mean third party mods.
If there is an unsinstall link then uninstall from that (you know, the one in Control Panel).
Otherwise just delete the files - the next time you start Steam is should detect that it has been removed.
With "official" steam games there is an option to "remove local game content" if I remember correctly. This is a posh way of saying delete the files :D
Thankyou squire!