This function is found under Settings> Manage Labels.
Edit a Label
You can edit existing labels in the Manage Labels page by following these steps.
Step 1 — In the main menu, navigate to Settings > Manage Labels.
Step 2 — In the label list, click the Edit button for the label you would need to change.
Step 3 — Edit the label fields, as necessary.
Step 4 — Click the Save Label button to commit your changes.