In Fonzip, you can assign tags to personal & institution records in 3 ways.

After applying your filters from the Users & Companies section and filtering the people you want to add / remove tags, select Add / Remove Tag for operations.

Click the Operation button next to the label you want to add / remove in the window that appears. Select Tag if you want to assign tags, or Remove Tag if you want to remove the tag from people.

Your operation will be queued and you will be notified by the system when it is finished.

To process a tag on a person or organization record, enter their profile

To add tags, choose Operations > Apply Tags.

Press the Tag button on the right of the label you want to assign on the screen that appears.

To remove a tag, press the X button to the right of the tag you want to remove in the Tags section under the Contact profile.

If you choose Yes on the warning screen, the tag will be removed from the person.

For detailed information: How Are Tags Added?