You can edit the name and color of an existing label.
On GitHub, navigate to the main page of the repository.
Under your repository name, click Issues or Pull requests.
Next to the search field, click Labels.
In the labels list, click Edit next to the label you want to edit.
In the text box, type your new label name.
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.