Bulk clear notifications

There was a video explainer showing how to bulk close all of the updates in the inbox. When I do this it clears the updates by board. But when I log back in all the updates are there.

I have 30,000 updates that need to be cleared is there a way I can do this in bulk any help would be appreciated.

It appears doing it by board does work, but there is a limit to the total updates it will close at any one time.

It seems to me that is roughly 1000 updates per clear.