removed dangling variable and cleaned up space

src/powershell-run/main.cs

@@ -161,13 +161,11 @@ namespace Microsoft.Samples.PowerShell.Host
                 executeHelper(initialScript,null);
         }
 
-        private string _prompt;
-
         /// Sets the prompt equal to the output of the prompt function
         public string Prompt(Runspace rs)
         {
-            string returnVal  = string.Empty;
-            Pipeline pipeline        = rs.CreatePipeline();
+            string returnVal      = string.Empty;
+            Pipeline pipeline     = rs.CreatePipeline();
             Command promptCommand = new Command("prompt");
 
             pipeline.Commands.Add(promptCommand);