I kept getting notified that there was an update for Nuget, but everytime I tried to install the update, the installation would fail with the following message:
The signature on the update version of 'NuGet Package Manager' does not match the signature on the installed version. Therefore, Extension Manager cannot install the update.
And when I tried to uninstall the Nuget package manager manually, the uninstall button would appear greyed out.
The solution I found was to right click on the Visual Studio shortcut and open it up in Administrative mode. In admin mode, I was able to uninstall Nuget and then was successfully able to install the newest version of Nuget.
Now you know!