Suppose we have already Employee Self-Service Portal configured in our Dynamics 365 Instance.

Now we would like to have Customer Self-Service Portal instead of Employee Self-Service Portal associated to our instance. To configure this, we need go to Admin Centre à Select Portal and Click on Manage.

Then select Manage Dynamic 365 CRM Instance and then Update Dynamics 365 Instance

From there we can select the Portal Audience and corresponding Portal to be deployed.

This will install the corresponding portal solution to our CRM Instance.

Now we have successfully set Customer Self-Service Portal. So to switch to Customer Self Service Portal, we can select Portal Details and Update Portal Binding to point it to website we want it to bind to. Now from drop down list we select Customer Self-Service as
the web site record and click on Update.

Once update is done, opening the Base Portal URL will open up Customer Self-Service Portal instead of Employee Self-Service Portal now.