https://learn.microsoft.com/en-us/dotnet/api/system.windows.controls.itemscontrol.system-windows-controls-primitives-icontainitemstorage-clearvalue?view=netframework-4.8.1&viewFallbackFrom=windowsdesktop-9.0
ItemsControl.IContainItemStorage.ClearValue(DependencyProperty) Method (System.Windows.Controls) |...
Removes the specified property from all property lists.
methodsystemwindowscontrols