JavaScriptでオブジェクトのプロパティを削除するにはどうすればよいですか？

以下は、JavaScriptでオブジェクトのプロパティを削除するためのコードです-

例

<!DOCTYPE html>
<html lang="en" >
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
   body {
      font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
   }
   .result,.sample {
      font-size: 20px;
      font-weight: 500;
   }
</style>
</head>
<body>
<h1>Delete object properties in JavaScript</h1>
<div class="sample">Before Deleting <br /></div>
<div style="color: green;" class="result">After deleting<br /></div>
<button class="btn">CLICK HERE</button>
<h3>
Click on the above button to delete object properties
</h3>
<script>
   let btnEle = document.querySelector(".btn");
   let resEle = document.querySelector(".result");
   let sampleEle = document.querySelector(".sample");
   let obj = {
      firstName: "Rohan",
      lastName: "Sharma",
      welcome() {
         return "Welcome " + this.firstName + " " + this.lastName;
      },
   };
   function beforeDelete() {
      sampleEle.innerHTML += "obj.firstName = " + obj.firstName + "<br>";
      sampleEle.innerHTML += "obj.lastName = " + obj.lastName + "<br>";
      sampleEle.innerHTML += "obj.welcome() = " + obj.welcome() + "<br>";
   }
   beforeDelete();
   btnEle.addEventListener("click", () => {
      delete obj.firstName;
      delete obj.lastName;
      delete obj.welcome;
      resEle.innerHTML += "obj.firstName = " + obj.firstName + "<br>";
      resEle.innerHTML += "obj.lastName = " + obj.lastName + "<br>";
      try {
         resEle.innerHTML += "obj.welcome() = " + obj.welcome() + "<br>";
      }
      catch (err) {
         resEle.innerHTML += err;
      }
   });
</script>
</body>
</html>