Android: How to remove customize keyboard button from keyboard?

Please find below the screenshot wherein the circular box shows the customize button option.

XMl Code:

<EditText
        android:id="@+id/et_cost_per_mile"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center_vertical"
        android:hint="Cost Per Mile(₤)"
        android:inputType="numberSigned"
/>

All I want to remove :: button from keyboard.

from Android: How to remove customize keyboard button from keyboard?