To manage tags on a single contact:
Navigate to the contact record
Click the edit icon to open the contact editor
Scroll to the tags section and either delete a tag(s) or begin typing to search for the tag you want to add.
To add a new tag to the list, simply type the name of the tag and hit "ENTER". It will then be available as an option for future use.
Click Save and you're done.
To remove tags in bulk:
Visit the contact list and search for the tag, click the "Filter" button, or click on the tag name next to any contact. This will filter the list to only contacts with this tag.
Once your list is filtered, check the box in the upper left of the contact table to select all contacts, or click on individual contacts from the list.
Once you've selected all the contacts, click manage tags and add or remove tags from the selected contacts.
Video: Managing Tags in Shaker
Troubleshooting:
I'm trying to add a new tag, but it won't save: Make sure after typing the tag name, you hit "ENTER" before saving.