If you'd like to send an email to your subscribers in Hive, except for a certain group, you can exclude these users when choosing who to send the email campaign to.
1) When building a new one-time email campaign, the first step you'll be taken to is the "Choose Recipients" step.
2) To exclude a certain group of subscribers, click View All Filters and filter for the segment or group you'd like to exclude from the email send (e.g; those who live in a specific region).
3) Toggle the "are in the" parameter to "aren't in the".
This will send the email to all of your subscribers, except the users who match the segment/filter you're looking to exclude.