Alternate Nr. 1:
Make a:
hitcircle.png = transparent
hitcircleoverlay.png = transparent
hitcircleoverlay-0.png = create a your Hitcircle without Numbers (or pick one your like and rename hitcircleoverlay.png to hitcircleoverlay-0.png
change your Skin.ini:
HitCircleOverlayAboveNumbers: 0 to 1
default-0.png ... 9 normal Numbers without Circle
Alternate Nr. 2:
Make a:
hitcircle.png = transparent
hitcircleoverlay.png = transparent
Make a default-0.png to default-9.png as hircircle. (Size must be 160x160px for SD or 320x320px for HD @2x)
Change your Skin.ini:
[Fonts]
HitCircleOverlap: 160