Unsubscribe a group of users from all feeds

One way is to uncheck the "show in catalog" option and also remove the user group from the Feed security. This will remove the user in the specified groups not to receive the feed. But, you need to do it for all the feeds where you want the user groups to be removed.

Thanks . If i uncheck the "show in catalog" option , it will be affecting all groups correct ? I already removed the user group from the Feed security.

Yes, you are right.

The security of the feed with the "show in catalog" controls who can see the news posts so if you remove the group then that will limit their access. This would need to be repeated for each feed.