Android remove ActionBar / TitleBar

I want to remove the action bar/ Title bar from my app to make it full screen. Below is the method which helped.

#Method 1

<application    android:allowBackup="true" 

   android:icon="@mipmap/ic_launcher"   

 android:label="@string/app_name"  

  android:supportsRtl="true"    

android:theme="@style/Theme.AppCompat.Light.NoActionBar">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

I just changed the theme with NoActionBar and it worked.