You can edit the name and color of an existing label.
On GitHub Enterprise, 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.
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.