uninstall nuget package that no longer exists

We had our nuget server die and the admin never made a backup. So now building on a new install won't work b/c there is nothing in the cache and it can't recreate the dependency list. I tried to force uninstall but it says that I have to restore the package before uninstalling it so it can build the dependency tree. Argh. I just want the package out of the solution so we can rebuild the site. I also tried removing it from packages.config but that didn't help.

Is there a way to manually force delete a nuget package without having access to it anymore? Otherwise I need to build a new solution from scratch and migrate the files over.

Here are the commands I tried:

uninstall-package packagename -RemoveDependencies -force

and

uninstall-package packagename -force

Here is the config file:

<?xml version="1.0" encoding="utf-8"?>
<packages>
  <package id="custom.serialization" version="2017.3.20.142224" targetFramework="net462" />
  <package id="custom.themes.flat-blue" version="2016.12.9105400" targetFramework="net452" />
  <package id="Microsoft.AspNet.Cors" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.Mvc" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.Razor" version="3.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebApi" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebApi.Client" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebApi.Core" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebApi.Cors" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebApi.WebHost" version="5.2.3" targetFramework="net452" />
  <package id="Microsoft.AspNet.WebPages" version="3.2.3" targetFramework="net452" />
  <package id="Microsoft.Web.Infrastructure" version="1.0.0.0" targetFramework="net452" />
  <package id="Newtonsoft.Json" version="10.0.2" targetFramework="net462" />
  <package id="NLog" version="4.4.5" targetFramework="net462" />
  <package id="NLog.Extended" version="4.0.0.1" targetFramework="net452" />
  <package id="NLog.Web" version="4.4.0" targetFramework="net452" />
</packages>

Thanks