I have an account on Coderwall, and it lists GitHub repos that I deleted long time ago. As a result, all the links point to 404 pages on Github.
This happens on renaming repositories on GitHub as well. On Coderwall, they list it as 2 separate repos and one of them is invalid.
I couldn't find any way in the settings to delete a repository or refresh the repo list from GitHub.
Best Answer
You will have to contact Coderwall Support as this is done manually and per account on their side.
When I contacted them they fixed the issue within a day.
Their reply to me: