[github] Delete a closed pull request from GitHub

I accidentally made a wrong pull request and ended up closing the request myself. It's in a closed state right now but it's accessible via direct URL and showing on my activity bar.

Is there any way to delete a pull request completely so it's no longer accessible via URL or shows up on your activity history?

This is the reply I received from Github when I asked them to delete a pull request:

"Thanks for getting in touch! Pull requests can't be deleted through the UI at the moment and we'll only delete pull requests when they contain sensitive information like passwords or other credentials."

5 step to do what you want if you made the pull request from a forked repository:

1. reopen the pull request
2. checkout to the branch which you made the pull request
3. reset commit to the last master commit(that means remove all you new code)
4. git push --force
5. delete your forked repository which made the pull request

And everything is done, good luck!