To remove a subscriber from an existing tag, do the following:
Click onto the Subscribers tab, and then the Search subtab.
Search for the email address of the specific subscriber.
With the email address selected, click the ‘tags’ button along the bottom of the page.
A window opens with the option to add or remove tags.
Type in, or choose from a list of tags, the name of the tag(s) to be removed.
Save your selections to remove the tag.