'Declaration Public Property AllowRecurring As Nullable(Of Boolean)
public Nullable<bool> AllowRecurring {get; set;}
Note that this property doesn't prevent existing recurring activities from being displayed. It simply disallows the user from creating recurring activities through the UI.
Target Platforms: Windows 10, Windows 8.1, Windows 8, Windows 7, Windows Server 2012, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2