Add more sources at your own risk.
(Doing this is not recommended.)
Repositories can stay "stuck" when you don't need them anymore, it can make the source undeletable. If this happens to you, manually delete your source by removing it from the sources list (/private/etc/apt/sources.list.d/cydia.list), and then remove it from Cydia's Metadata (/private/var/lib/Cydia/Metadata.plist).