Hi Oihana,
Sorry that there is no way to hide the ball - speedy scrollbar.
The speedy scrollbar is a tool added by PowerServer Mobile to help scroll quickly through a long list of data records. In the DataWindow control, the user can use the speedy scroll bar to scroll through a large amount of data page by page, instead of row by row. The speedy scroll bar automatically appears when the user swipes up or down in a DataWindow. The speedy scroll bar will disappear if it is not used for 2 seconds.
Regards,
ZhaoKai