Immutable state; remove property based on key which is passed;

removeProperty.js

var state = {
  0: "zero",
  1: "one",
  2: "two",
  x: "hello"
};

function removeByKey (myObj, deleteKey) {
  return Object.keys(myObj)
    .filter(key => key !== deleteKey)
    .reduce((result, current) => {
      result[current] = myObj[current];
      return result;
  }, {});
}
console.log("Current State:");
console.log(state);

var stateMinusFirst = removeByKey(state, "0");
console.log("State minus zero key:");
console.log(stateMinusFirst);

var stateMinusX = removeByKey(state, "x");
console.log("State minus x key:");
console.log(stateMinusX);