github
I forked a GitHub repo and submitted a Pull Request. But now my account still has a copy of the original repository.
Must I have that repo on my account enabled/present until the merge is done or I can delete it?
Since I don't plan to add more features it would be a waste of space.
See Deleting a repository, from Help.GitHub.
Go to the repo's Settings page
Scroll to the bottom of the page and click "Delete this repository"
Read the warnings and enter the name of the repository you want to delete
Click "I understand the consequences, delete this repository"
Deleting a public repo will leave the forks, but if it was private, then all its forks would also be deleted.
Your wish is their new feature
If the commit is not on the default branch, the indicator will show the branches which contain the commit. If the commit is part of an unmerged pull request, a link will be shown.
Once the commit makes it to the default branch, any tags that contain the commit will be shown, and the default branch will be the only branch listed.
Best Answer
You must keep the forked repo around until the merge is done; otherwise, GitHub will not keep your changes.
Additionally, it isn't really a waste of space since GitHub allows unlimited open repos for no cost, and lesser used repos drop off the list of recently contributed repos on the front page, so you won't ever see it.
If you are talking about your local checkout of the fork, there is absolutely no need to keep that. All your changes are now stored on GitHub, so what you do with the local copy doesn't matter - just don't delete the repo on GitHub before the PR is merged.