To unlink a GitHub pull request from a Xebrio bug, go to the details window of the specific Xebrio bug. Navigate to the GitHub tab, and then to the Pull Requests secondary tab. For the GitHub pull request to be removed, click on it's three dot vertical menu and select the Unlink Pull Request option.
Users will need view and edit permissions in the bugs module to perform this action. Depending on the user's project permission settings, they may be able to view all project bugs or just a subset. Watchers specifically added to the bug will be able to view it.