From what I know, the Start purge work for Start8, Start10 and Start11, so I believe, it is normal to see some error messages popup on the CMD windows, when there are some files don't exist for that specific version to be deleted. But, Start11 should be removed once all the steps are done and reboot after that. Please rerun the purge and let is finish doing its job with all the error appear. Just let it go through everything and don't reboot when ask until everything. Only reboot after "purge complete" message box appear. Click OK than reboot.
Thank you,
Basj,
Stardock Community Assistant