To close a pull request in GitHub, follow these steps:
- Click on the 'Pull requests' tab near the top of the repository page.
- Locate and click on the box next to the pull request you wish to close.
- Go to the 'Mark as' option and click the drop-down arrow.
- Click on the 'Closed' button.
- Go to the 'Closed' section.
- The pull request will now be marked as 'Closed' and will no longer be active or considered for merging.