title: Scala how to remove item while matching other list itme
body: <p>I have a 2 list of following class</p>
  
  <pre><code>  case class User(var userId: Int =0,
                  var userName: String ="",
                  var email: String="",
                  var password: String ="") {
    def this() = this(0, "", "", "")
  }
  </code></pre>
  
  <p>globalList of User class.</p>
  
  <p>localList of User class.</p>
  
  <p>I would like to remove/filter all items from globalList that are same userId in localList.</p>
  
  <p>I tried couple of api with no success such as filterNot, filter, drop, dropWhile. Please advice me how it can be done.  </p>