Removing GitHub repository and adding new GitHub account

[tcmburgoyne]

Description of Bug

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My friend added his git hub repository to my stackblitz to help me with a project. We want to remove his account but couldn't see a way how to. I emailed support last night and then this morning I'm seeing no repository on my stackblitz account. I tried adding my github and got this error message:
"It looks like you already attached a different provider account to your StackBlitz account
We only support the connection of a single external account for each Git service provider.

If you think this is a bug/problem on our end, please file an issue over at https://github.com/stackblitz/core"

Steps to Reproduce

1. Go to stackblitz repositories
2. Add a repository
3. Try to remove a repository (not currently possible it seems, support@ email might have done it for me)
4. Try to add a new repository
5. Authorize then connection on github
6. Error messages is given by stackblitz

Expected Behavior

A clear and concise description of what you expected to happen.
GitHun repository can be easily removed and added

Screenshots/Screencast

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See above

Additional Context/Questions
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