title: How to get rids of nuget packages which is OK to delete. (Xamarin.Forms)
body: <p>Everytime when I update XF or Platforms, some built-in nugets are appeared in my nuget Packages list.</p>
  
  <p>For example, System.Collections, System.Diagnostics.Debug, System.Linq and many many.
  These kind of things were not in the nuget Packges list before. But I thought it's necessary.</p>
  
  <p>And I noticed that package list of XF project just created are very clean.
  It does not seems a big problem but it's annoying.</p>