If you haven't look at this article yet, you may want to. It helps you understand what tags are and how they work in the Hatchbuck system.
Below are the ways to automatically and manually add or remove tags from contacts.
Tags Included in Spreadsheet
Tags should be separated by commas in the same cell or into separate columns. This is helpful if contacts may have differing tags.
Add Same Tag to Every Contact
On the Set Defaults page of import, choose a tag or create new one that will apply to the entire file. This is in addition to what you may have mapped from your spreadsheet.
You can choose to Tag a Contact or Remove a Tag as an automation on campaigns, email templates, online forms, webpage tracking, tag rules, and purchase rules.
Manually (from the Contact Record)
In the Contact Record, click the blue + circle to add. Type in the box to find an existing tag, or create a new one.
To remove a tag, click on the tag name to turn it blue, then click the X to delete
Manually (from the Contact List View)
In the Contacts Tab, filter for and then select the contacts you would like to add or remove the tag.
Select the orange Actions drop-down at the top of the screen and select to add or remove tags.
Manually (from Account Settings)
If you would like to add a tag to your database without specifically tying it to a contact right away, or if you would like to remove a tag all together, head to account settings > customizations > tags.
Create a new tag by clicking the + New Tag button in the right corner, or remove a tag by clicking the tag name to turn it blue, then using the "x" to select "remove."