Welcome to the community, @Victoria_Harvey!
Expand the record that you want to stop watching (i.e. stop receiving notifications for), open the activity panel on the right (if it’s not already showing), click on the RSS icon at the top, then choose “Not Watching”.
Fat thanks so much @ScottWorld - but its more to do this on behalf of other team members, ie my senior boss who doesnt go into the feed unless he’s mentioned and then doesnt want to be bothered again. Can I unsubscribe him from further notifications?