Yes in fact you can uninstall WMC through "Turn windows features on and off" but you still won't be able to revert back to a non-WMC Pro key. At least as far as I know. I'm in the same situation that you are. Seems WMC is the only activation that won't work atm. If anyone knows of a way to revert Win 8 Pro WMC edition back to Win 8 Pro without a full Windows reinstall from scratch, it would be greatly appreciated. thanks all.
downgrade from w8 pro wmc to w8 pro: regedit hkey local machine => software => microsoft => windows nt => current version export current version reg backup change edition id from "ProfessionalWMC" to just "Professional" run install disk select "upgrade" it should bypass the "unable to downgrade" checker if it's able to complete compliance check if that doesn't fix 100% you may have to delete the "WMC" in the digitalproductid4 binary note: this has taken from somewhere in this forum.
Windows 8 Pro, Spanish language pack. Activated with the gogoCLIENT program and the recommended ipv6 settings until Feb 9th, 2012 Moonrak