How to enable user to close the banner ad?

i have seen this article.Close button for AdMob banner

Recently i have downloaded an app..in that there is X button on top left side of the app to close Ad.How can i implement that feature.

This is how my code looks

<RelativeLayout xmlns:ads="http://schemas.android.com/apk/lib/com.google.ads"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context=".MainActivity" >

    <!-- Header -->

    <TextView
        android:id="@+id/Header"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="10dp"
        android:textAppearance="?android:attr/textAppearanceMedium"
        android:textColor="#0585C2"
        android:textSize="16sp"
        android:textStyle="bold" />

    <!-- Expandable list characteristics -->

    <ExpandableListView
        android:id="@+id/expandable_list"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:childDivider="@android:color/white"
        android:divider="@android:color/darker_gray"
        android:dividerHeight="2dp"
        android:fadingEdge="none" />

    <com.google.ads.AdView
        android:id="@+id/adView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        ads:adSize="BANNER"
        ads:adUnitId="a1523adgakdggak"
        ads:loadAdOnCreate="true"
        ads:testDevices="TEST_EMULATOR,022b1ahhddlkahda" />

</RelativeLayout>

--Please help me out

Solution

After days of research ,finally figured out that we cant do that in xml and also only some specific ad networks are providing that close(x) feature.Basically i am using ad mob....so for now we cant add X button(or admob is not providing that feature)...Lets hope..in future admob enables us to use that feature..:)...