Two options for Formik method additions based off of existing Formik code

formik.js

function deleteField(obj: any, path: string) {
  let res = clone(obj); // this keeps inheritance when obj is a class
  let resVal = res;
  let i = 0;
  let pathArray = toPath(path);

  for (; i < pathArray.length - 1; i++) {
    var currentPath = pathArray[i];
    let currentObj = get(obj, pathArray.slice(0, i + 1));

    if (currentObj && (isObject(currentObj) || Array.isArray(currentObj))) {
      resVal = resVal[currentPath] = clone(currentObj);
    } else {
      const nextPath = pathArray[i + 1];
      resVal = resVal[currentPath] =
        isInteger(nextPath) && Number(nextPath) >= 0 ? [] : {};
    }
  }

  delete resVal[pathArray[i]];

  // If the path array has a single element, the loop did not run.
  // Deleting on `resVal` had no effect in this scenario, so we delete on the result instead.
  if (i === 0) {
    delete res[pathArray[i]];
  }

  return res;
}

function replaceField(obj: any, path: string, newKey: string, newValue: any) {
  let res = clone(obj); // this keeps inheritance when obj is a class
  let resVal = res;
  let i = 0;
  let pathArray = toPath(path);

  for (; i < pathArray.length - 1; i++) {
    var currentPath = pathArray[i];
    let currentObj = get(obj, pathArray.slice(0, i + 1));

    if (currentObj && (isObject(currentObj) || Array.isArray(currentObj))) {
      resVal = resVal[currentPath] = clone(currentObj);
    } else {
      const nextPath = pathArray[i + 1];
      resVal = resVal[currentPath] =
        isInteger(nextPath) && Number(nextPath) >= 0 ? [] : {};
    }
  }

  delete resVal[pathArray[i]];

  resVal[newKey] = newValue;

  // If the path array has a single element, the loop did not run.
  // Deleting on `resVal` had no effect in this scenario, so we delete on the result instead.
  if (i === 0) {
    delete res[pathArray[i]];
    res[newKey] = newValue;
  }

  return res;
}