Describes the cause and action for error messages.
Error Message(English)：
how to cancel pull request
How to cancel a pull request on github? - Stack Overflow
https://stackoverflow.com/questions/5385567/how-to-cancel-a-pull-request-on-github
Delete file from Pull Request on GitHub
https://stackoverflow.com/questions/9498201/delete-file-from-pull-request-on-github
Delete a closed pull request from GitHub
https://stackoverflow.com/questions/18318097/delete-a-closed-pull-request-from-github
How to close a GitHub pull request with a commit message?
https://stackoverflow.com/questions/23015168/how-to-close-a-github-pull-request-with-a-commit-messag・・・
git revert changes and cancel pull request
https://stackoverflow.com/questions/21563845/git-revert-changes-and-cancel-pull-request
GithubのPullRequestを取り消したい --deleteオプション - Qiita
https://qiita.com/Yorinton/items/adf1ebf922c26ddb26a0
GitHub 初歩的な不具合解消法 - Qiita
https://qiita.com/y-matsuya/items/1565d4c1551e0729c2b5
GithubでPull Requestは絶対消せない。ヤバい＼(^o^)／ｵﾜﾀ - アジャイル ...
https://sinsoku.hatenablog.com/entry/2013/10/16/013106
【git】pull requestを出す前 or 出した後の取り消し - tweeeetyのぶろぐ的めも
http://tweeeety.hateblo.jp/entry/2015/06/10/220841