Hello Luis,
You can try the following:
Color transparentColor = Color.Transparent;
nRichTextLabel1.FillInfo.FillStyle = FillStyle.Solid;
nRichTextLabel1.FillInfo.Color = transparentColor;
nRichTextLabel1.PaletteInheritance = PaletteInheritance.None;
nRichTextLabel1.Palette.ControlBorder = transparentColor;
Best Regards,
Nevron Support Team