Make ADO.NET (and EntityFramework) database release

I'm creating and dropping databases on the fly for some integration tests. I am doing all my database management at the ADO.NET layer. For tests, I use Entity Framework because entities are one part of what I am testing. The problem is that after this:

using (ProjectEntities db = new ProjectEntities(cs)) {
}

      

        
        
        
      

    

I can no longer drop the database. He says he is being used. How to release it so that it can be dropped?

I had the same problem at the ADO.NET layer and did this:

new SqlCommand("USE [master]", DatabaseConnection).ExecuteNonQuery();

      

        
        
        
      

    

but I'm not sure how to accomplish something with the same effect for an Entity Framework connection. I am trying to manually delete the db object (although the use clause should guarantee this) and I also tried to manually close the db.Connection. Nothing helped. If I could work directly with SQL without connecting to the Entity Framework, I believe I can do it. Or maybe there is another way?