I am also getting this error, when I look under sources I have repo666.ultrasnow.com, when I select it I then click on ultrasnow, the option on the top right says INSTALL instead of modify. How do I delete it?
You have to delete the entire source itself. You don't open the UltraSn0w repo, you tap edit on the top right corner, or, you slide from right to left on the repo itself, then tap the delete button.