Well uninstalling a vWii WAD file to install a Wii WAD probably won't end well. vWii & Wii WADs are different and incompatible with each other. Is your Wii banner bricked? That's easily fixed. If not, a Wii is very cheap these days. You should buy a replacement. If better to do that then brick the Wii U's Wii menu
I know this is quite late but just to save anyone's time who is also looking to get the non-crippled/original version of the Mii Channel on their vWii, I can confirm that the regular Wii Channel does work fine in my practices (apart from the WiiConnect24 Parts). I would still always recommend a NAND Backup before installing/removing any WAD's from any Wii(I am not responsible if you end up bricking your vWii)
I made a backup of the vWii Mii Channel using 'Yet Another BlueDump MOD' and simply removed the original Mii Channel using 'AnyTitleDeleter'. Then I downloaded the latest version of the Mii Channel WAD using NUS and installed it to the vWii using 'WiiModLite' as I could not get MMM to work.
All of my Mii's stayed after install of the original Mii Channel but I was required to go through the tutorial on making my "first mii" which I just deleted after.