Hi,
You can use the following procedure to remove a role:
In the Configuration Manager console, go to the Administration workspace. Expand Site Configuration, and then select the Servers and Site System Roles node.
Select the site system server with the role to remove. In the Site System Roles details pane, select the target role.
In the ribbon, on the Site Role tab, in the Site Role group, select Remove Role. Confirm that you want to remove the role.
I hope the above information is helpful to you.
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Best regards,
Larry