Making a function using .replace() to remove multiple characters in a variable string?

The function accepts 3 inputs: (string (str), starting point in string (index), and how many characters to remove after that (count)).

function removeFromString(str, index, count) {
  let newStr = '';
  for (let i = index; i <= (index + count); i++) {
    newStr = str.replace(str[i], '');
  }
  return newStr;
}

It’s returning outputs that may remove one character at most, but nothing more than that, which is not what I am trying to achieve.

What I want is a function that when called, will return a function without the characters specified from the index and count parameters.