It is not possible to delete a pull request yourself - you and the repo owner (and all users with push access to it) can close it, but it will remain in the log. This is part of the philosophy of not denying / hiding what happened during development.
However, if there are critical reasons for removing it (this is basically a violation of the Github Terms of Service), the Github support team will delete it for you.
Regardless of whether you want to remove your PR for you, you can easily ask them, just write them an email at support@github.com.
Nevik Rehnel Aug 19 '13 at 16:16 2013-08-19 16:16
source share