In repositories where you have write access, you can edit the name, color, and description of an existing label.
On GitHub, navigate to the main page of the repository.
Under your repository name, click Issues or Pull requests.
Above the list of issues or pull requests, click Labels.
In the labels list, next to the label you want to edit, click Edit.
In the text box, type your new label name.
Type a description to help others understand and use your label.
A color is automatically selected for the label. You can customize this color by editing the hexadecimal number or clicking the refresh button for another random selection.
Click Save changes.