When you need a RadDropDownList to appear empty and non-interactive, the most dependable approach is to clear the selection, remove all items, and then disable the control. Telerik controls maintain state aggressively, so performing all three steps ensures the UI reflects the change immediately and doesn't repopulate itself on the next postback.
Here's the exact pattern:
ddlPackageCount.ClearSelection()
ddlPackageCount.Items.Clear()
ddlPackageCount.Enabled = False
1. ClearSelection()
This removes any currently selected item. Even if the dropdown is later disabled, Telerik will still show the previously selected value unless you explicitly clear it. This call guarantees the control has no active selection.
2. Items.Clear()
This wipes out the entire Items collection. It's the most direct way to ensure the dropdown displays as empty. Because this approach doesn't rely on data binding, it works consistently whether the control was populated manually, through a DataSourceID, or via NeedDataSource.
3. Enabled = False
Finally, disabling the control prevents user interaction and visually communicates that the dropdown is no longer available. Telerik applies its built-in disabled styling automatically, so no additional CSS is required.