Ivan S. Shcherbakov
To uninstall WinCDEmu, simply go to Control Panel -> System -> Hardware -> Device Manager. Then select "IDE ATA/ATAPI Controllers -> Virtual Disk Enumerator". Afterwards, right click and select "Uninstall". That is all. Additionally, you'll need to select another program to open ISO files in Explorer (or just reinstall another CD/DVD emulator that does it automatically).
And, yes, you can safely remove the WinCDEmu folder in Program Files afterwards. Automatic uninstallation will be added in future versions.