User blog comment:Mathmagician/Installing Reborn Mod - Walkthrough/@comment-4674838-20120427232237

To uninstall, you can go to where your copy of Terraria is normally installed and delete the folder, then redownload Terraria through Steam. You will need to find this folder on your computer yourself, because it's different for different systems. By default, it's probably in a location such as C:\Program Files (x86)\Steam\steamapps\common\terraria.