ArcGIS Pro 2.7 API Reference Guide
MoveBookmark Method
Example 

ArcGIS.Desktop.Mapping Namespace > Map Class : MoveBookmark Method
The bookmark to move.
The new index to move the bookmark to.
Moves the bookmark to a new index in the map's collection of bookmarks. This method must be called on the MCT. Use QueuedTask.Run.
Syntax
public void MoveBookmark( 
   Bookmark bookmark,
   int newIndex
)
Public Sub MoveBookmark( _
   ByVal bookmark As Bookmark, _
   ByVal newIndex As Integer _
) 

Parameters

bookmark
The bookmark to move.
newIndex
The new index to move the bookmark to.
Exceptions
ExceptionDescription
This method or property must be called within the lambda passed to QueuedTask.Run.
Example
Move a bookmark for a map with a given name to the top.
public Task MoveBookmarkToTopAsync(Map map, string name)
{
  return QueuedTask.Run(() =>
  {
    //Find the first bookmark with the name
    var bookmark = map.GetBookmarks().FirstOrDefault(b => b.Name == name);
    if (bookmark == null)
      return;

    //Remove the bookmark
    map.MoveBookmark(bookmark, 0);
  });
}
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

Map Class
Map Members