android kotlin - ConstraintLayout remove constraint programmatically

MainActivity.kt

package com.cfsuman.kotlintutorials

import android.os.Bundle
import android.widget.*
import androidx.appcompat.app.AppCompatActivity
import androidx.constraintlayout.widget.ConstraintLayout
import androidx.constraintlayout.widget.ConstraintSet
import androidx.constraintlayout.widget.ConstraintSet.*


class MainActivity : AppCompatActivity() {
    private lateinit var context:MainActivity

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Get the context
        context = this

        // Get the widgets reference from XML layout
        val rootLayout = findViewById<ConstraintLayout>(R.id.rootLayout)
        val textView = findViewById<TextView>(R.id.textView)
        val button = findViewById<Button>(R.id.button)

        button.setOnClickListener {
            val constraintSet = ConstraintSet()
            constraintSet.clone(rootLayout)

            // Remove text view top constraint
            constraintSet.clear(
                textView.id, // widget to remove constraint
                TOP // the Anchor to remove constraint from
            )

            // Finally, apply the constraint set to layout
            constraintSet.applyTo(rootLayout)
        }
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/rootLayout"
    android:background="#DCDCDC"
    android:padding="24dp">

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Remove TextView Top Constraint"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="300dp"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:background="#FEFEFA"
        android:fontFamily="sans-serif"
        android:padding="12dp"
        android:text="Lorem ipsum dolor sit amet, consectetur
         adipiscing elit."
        android:textColor="#333399"
        android:textSize="24sp"
        android:textStyle="italic"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button" />

</androidx.constraintlayout.widget.ConstraintLayout>