How to delete/detect any emoji as a whole from a string in Flutter?

I would like to simulate a keyboard backspace delete event from a string in Flutter (or Dart). Something like:

String str = "hello🇵🇬你们😀😀👨‍👩‍👦"myBackspace(str) // will return "hello🇵🇬你们😀😀"myBackspace(str) // will return "hello🇵🇬你们😀"myBackspace(str) // will return "hello🇵🇬你们"myBackspace(str) // will return "hello🇵🇬你"myBackspace(str) // will return "hello🇵🇬"myBackspace(str) // will return "hello"myBackspace(str) // will return "hell"