This article is designed to describe how to remove users in the below screenshot via powershell instead of using UI.
Disclaimer: information displayed in screenshots are Citrix test server data.

Instructions

Run Power Shell as administrator on any Delivery Controller and execute the following commands:

asnp citrix*
Get-BrokerAccessPolicyRule -DesktopGroupName "DesktopGroupName" | Set-BrokerAccessPolicyRule -RemoveIncludedUsers domain\user -AllowedUsers Filtered

Note: Replace the deliverygroupname and domain\user to the actual value in your environment.