Error 29501 When Uninstalling Citrix

Hello,
I am getting the following error message when Uninstalling Citrix Presentation Server. I am unable to find any resolution so I need your assistance to fix this issue. Please help me to find some way. I would be grateful to you. Thanks in advance.

Citrix Presentation Server for Windows Setup:
Updating System
The features you selected are currently being uninstalled.
Installer Information:
Error 29501: Setup has determined that Application Isolation Environments exist on this server. Remove all of these before continuing with uninstallation.Â
