So, Ghostscript is the kernel of PDFCreator.Versions 2.4 and 2.5 seem to work differently: 2.4 uninstall is complete, same with Architect 2.4, and in the context menu of the Windows Explorer I had "convert with PDFCreator" (with icon) which worked in the choosen profile. Uninstall of 2.5 could only be completed in Safe Mode when installed with Architect 2.5, and in the context menu "convert with PDFCreator" was replaced by "about PDFCreator" with icon, without any conversion option; I had to choose the general purpose "open with", and got the Ghostscript Error with ptotectect files I was the author of. when choosing one of my PDFCreator profiles. I understand that "convert" and "open" are different but don't understand why. The support don't mention anything about this.
A work around is to "print" an open protected file (in Adobe Reader) with MS XPS Document Writer; the password is removed.