1. @DomName('CSSStyleSheet.removeRule')
  2. @DocsEditable()
  3. @Experimental()
void removeRule(int index)

Source 

@DomName('CSSStyleSheet.removeRule')
@DocsEditable()
@Experimental() // non-standard
void removeRule(int index) =>
    _blink.BlinkCSSStyleSheet.instance.removeRule_Callback_1_(this, index);