deleteCharAt
fun StringBuilder.deleteCharAt(index: Int): StringBuilderRemoves the character at the specified index from this string builder and returns this instance.
If the Char at the specified index is part of a supplementary code point, this method does not remove the entire supplementary character.
Parameters
index - the index of Char to remove.
Exceptions
IndexOutOfBoundsException - if index is out of bounds of this string builder.