If you do not wish to show users, who recently joined your user portal, follow these steps.
Go to the Settings page in your Admin Panel.
Click on the Space Page on the left.
Scroll the right area down until you see the New Members block settings
Uncheck the "Show Block" setting under New Members and click Save.
If you have more than one public space, you would also need to click on the Home Page entry on this page and disable New Members there as well.