How to delete remote repository on github?

You can go to the main page of the repository and under your repository name, click "Settings"...

...and scroll down to the "Danger Zone"

Go to the settings page of your repo and the bottom you can find the "Delete this repository" button under the Danger Zone area. Enter your repository name to confirm the deletion and click "I understand the consequences, delete this repository" to confirm the operation. The url will endup like below if you visit the settings page of you repository,

https://github.com/GITHUB_USERNAME/REPOSITORY_NAME/settings

For example, if your name is john and have a repository named "sample_john" the url would look like this,

https://github.com/john/sample_john/settings

Warning: Doing the above operation will permanently delete your repository, wiki, issues, and comments, and remove all collaborator associations.