short version:
you can install the new version over the RC.
long version:
If you used the exe/installer for the RC and are going to use the exe/installer for the new version, then you don't need to uninstall the RC. If you are using the rar version of both, then you don't need to remove the RC files as the new version would replace them. If you used the exe/installer for the RC and want to use the rar of the new version, then you might want to uninstall the RC, as this removes the registry entries the installer creates, but you don't need to.