When you delete an integration (github), it takes minutes to be removed from the side menu.
Thank you for reaching out. Deletion of integrations happens in the background and therefore it can take a few minutes for it to be removed from the interface.
Due to other priorities we are unlikely to change the way integration deletions happen at this time.
:( that shouldnt take much. Just one or 2 lines of code. It is very bad UX, it was really confusing. Disappointed you wont fix this.