The NuGet command line tool (nuget.exe) does not contain a feature to delete local cache and packages but since is just a directory on your machine you can do this manually.

NuGet packages and cached files can be found here:

  • Mac OS X
    ~/.local/share/NuGet/Cache
    ~/.nuget/packages
    
  • Windows
    %LocalAppData%\NuGet\Cache
    %UserProfile%\.nuget\packages