Returns the receiver MutableBuffer with length characters deleted from the buffer beginning at the n'th character. If n is omitted, it defaults to 1. If length is omitted, or if length is greater than the number of characters from n to the end of the buffer, the method deletes the remaining buffer contents (including the n'th character). The length must be a positive integer or zero. The n must be a positive integer. If n is greater than the length of the buffer or length is zero, the method does not modify the buffer content.