public abstract class Element : ArcGIS.Desktop.Framework.Contracts.PropertyChangedBase, System.ComponentModel.INotifyPropertyChanged, System.IComparable, System.IEquatable<Element>  

//Find and element on a layout.

// Reference a layout project item by name
LayoutProjectItem layoutItem = Project.Current.GetItems<LayoutProjectItem>().FirstOrDefault(item => item.Name.Equals("MyLayout"));
if (layoutItem != null)
{
  QueuedTask.Run(() =>
  {
    // Reference and load the layout associated with the layout item
    Layout layout = layoutItem.GetLayout();
    if (layout != null)
    {
      //Find a single specific element
      Element rect = layout.FindElement("Rectangle") as Element;

      //Or use the Elements collection
      Element rect2 = layout.Elements.FirstOrDefault(item => item.Name.Equals("Rectangle"));
    }
  });
}

//Update an element's transparency using the CIM.

//Perform on the worker thread
QueuedTask.Run(() =>
{
  // Reference and load the layout associated with the layout item
  Layout layout = layoutItem.GetLayout();
  if (layout != null)
  {
    // Reference a element by name
    GraphicElement graphicElement = layout.FindElement("MyElement") as GraphicElement;
    if (graphicElement != null)
    {
      // Modify the Transparency property that exists only in the CIMGraphic class.
      CIMGraphic CIMGraphic = graphicElement.Graphic as CIMGraphic;
      CIMGraphic.Transparency = 50;             // mark it 50% transparent
      graphicElement.SetGraphic(CIMGraphic);
    }
  }
});

//Clone a layout graphic element and apply an offset.

//Perform on the worker thread
QueuedTask.Run(() =>
{
  // Reference and load the layout associated with the layout item
  Layout layout = layoutItem.GetLayout();
  if (layout != null)
  {
    // Reference a graphic element by name
    GraphicElement graphicElement = layout.FindElement("MyElement") as GraphicElement;
    if (graphicElement != null)
    {

      //Clone and set the new x,y
      GraphicElement cloneElement = graphicElement.Clone("Clone");
      cloneElement.SetX(cloneElement.GetX() + xOffset);
      cloneElement.SetY(cloneElement.GetY() + yOffset);
    }
  }
});

//Get element's selection count.

//Count the number of selected elements on the active layout view
LayoutView activeLayoutView = LayoutView.Active;
if (activeLayoutView != null)
{
  var selectedElements = activeLayoutView.GetSelectedElements();
  ArcGIS.Desktop.Framework.Dialogs.MessageBox.Show($@"Selected elements: {selectedElements.Count}");
}

//Set the active layout view's selection to include 2 rectangle elements.

//Reference the active view 
LayoutView activeLayoutView = LayoutView.Active;
if (activeLayoutView != null)
{

  //Perform on the worker thread
  QueuedTask.Run(() =>
  {

    //Reference the layout
    Layout lyt = activeLayoutView.Layout;

    //Reference the two rectangle elements
    Element rec = lyt.FindElement("Rectangle");
    Element rec2 = lyt.FindElement("Rectangle 2");

    //Construct a list and add the elements
    List<Element> elmList = new List<Element>
    {
      rec,
      rec2
    };

    //Set the selection
    activeLayoutView.SelectElements(elmList);
  });
}

//Clear the layout selection.

//If the a layout view is active, clear its selection
LayoutView activeLayoutView = LayoutView.Active;
if (activeLayoutView != null)
{          
  activeLayoutView.ClearElementSelection();
}

//Delete an element or elements on a layout.

//Perform on the worker thread
QueuedTask.Run(() =>
{
  //Delete a specific element on a layout
  aLayout.DeleteElement(elm);
 
  //Or delete a group of elements using a filter
  aLayout.DeleteElements(item => item.Name.Contains("Clone"));

  //Or delete all elements on a layout
  aLayout.DeleteElements(item => true);
});