Problem
Having been in the situation before where a Citrix installtion gets so in a mess that there is no option to remove, then this command comes in realy usefull as Presentation Server / Xen App can be a major pain to remove. Ive found this useful numourous times as the citrix unistall routing can fail and be very flakey.
Resolution
1. Simply at a command line run the following command. Where “MPS.msi” is the path of the MPS.msi in your install.
msiexec /x mps.msi /L*v c:\output.log CTX_MF_FORCE_SUBSYSTEM_UNINSTALL=Yes