To get started, navigate to your GitHub repository page.

On the repository home page, click on the Pull requests tab.

You'll need to select the closed pull requests to find one to revert.

Click on the pull request to open the detailed pull request information page.

Once you get to this page, hit the Revert button.

Finally, select "Create pull request" to finalize the revert. This will create a new pull request to revert the changes done by the previous merge. 

Sometimes you may need to revert a PR or pull request in GitHub. Perhaps your merge resulted in conflicts, or a pull request was made to the wrong branch. Either way, you can revert a pull request in a few simple steps.

How to Revert a PR in GitHub