Thank you for contacting us.
The easiest approach to properly hide the arrows would be to first set their Visiblity
property to Collapsed
(as I suppose you have already done). Then you can set the following Padding
to the RadScrollBarElement
I was not able to identify a similar border to the one you are describing in our RadScrollBarElement. If you let me know which theme you are using and/or what changes you have made I may be able to assist you further.
Looking forward to your reply.