Not able to clear the Feeds in Notification feed

My aim is to clear the notification feed. I use the following to do so

userPrivateFeed.unfollow('PrivateMessageBoardFlat', groupId, { keepHistory: false });

userPrivateFeed.follow('PrivateMessageBoardFlat', groupId, {limit: 0});

However this is not working and when I query the userPrivateFeed, all the previous activities are fetched.

Also point to note is that prior to these calls, I mark them read and seen. But when I fetch the activities from the feed after the above calls, all of them are unread and unseen. That makes me think that the unfollow with keepHistory worked, but the follow with limit did not work.