Hi Jay Jose,
You do not need to remove the children elements from a RadListBoxItem in order to add a UserControl. You can directly add the UserControl (with the help of RadHostItem) to the RadListBoxItem. Please note that the Virtualizaiton
of RadListBox should be turned off when you add user controls. In addition, a UserControl is a heavy object for a scrolling operation, so you may experience performance decrease while scrolling up and down.
If you have additional questions, feel free to contact me.
the Telerik team