To edit tags from the Calls Page:
Step 1: Navigate to “Calls” page from Portal
Step 2: Click on the tag icon of the instance, and you will be able to add, remove and edit tags from the Calls Page, clicking on the call ID will allow you to edit the tags from the Show Page.
To Edit tags from the Dialer History:
Step 1: Navigate to the Dialer and click on call History tab
Step 2: Click on call tag and edit the assigned tags or add new ones.