Hello Ramon De Klein,
Thank you for contacting us.
Yes, it is possible to hide the button or to make any modifications on the icon itself.
You need to edit the TimePicker in Expression Blend. Select it and go to Object > Edit Template > Edit a Copy
and you will see the template of the button. The button itself is named RadToggleButton x:Name="ToggleButtonElement".
However you will need to be careful while modifying this button or even completely removing it, because it keeps the drop down fuctionality of the TimePicker. You might need to wire up some custom logic to show the drop down pop-up.
In case you encounter any diffciulties or you have further questions, please get back to us, we will be glad to help.
the Telerik team
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