In this article I am going to show the steps to Hide “Redeem Invitation” option in Microsoft Portal Login Page.
Step 1 : Navigate to the Dynamics 365 Portals App

Step 2 : Goto the “Site Settings” Menu

Step 3 : Update the Value of the following Settings records from “True” to “False”
- Authentication/Registration/InvitationEnabled

Step 4 : Restart the portal and hit F5 on the Portal Brower to view the changes (View the following article for instructions on how to restart the Portal)

I Hope this article will help you in your day to day consulting work . If there are any questions please feel free to email or comment.