Remove underline from TextInputEditText

<style name="Theme.MyApp" parent="Theme.MaterialComponents.Light.NoActionBar">
    <item name="textInputStyle">@style/Widget.MyApp.TextInputLayout</item>
</style>

<style name="Widget.MyApp.TextInputLayout" parent="Widget.MaterialComponents.TextInputLayout.FilledBox">
    <item name="boxStrokeWidth">0dp</item>
    <item name="boxStrokeWidthFocused">0dp</item>
</style>

It looks like the Material Components library draws its own underline using app:boxStrokeColor. This attribute is a ColorStateList, so you have to create a color state list resource in which all states' colors are set to transparent. So basically you want to create a new file res/color/filename.xml:

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:color="@android:color/transparent"
        android:state_pressed="true"
        android:state_focused="true"
        android:state_selected="true"
        android:state_checkable="true"
        android:state_checked="true"
        android:state_enabled="true"
        android:state_window_focused="true" />
</selector>

and set the app:boxStrokeColor attribute to @color/filename.

However, this left me with a black underline which still doesn't respond to android:background=@null or <item name="colorControl*">@android:color/transparent</item>.

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TL;DR

Quickfix: if you set the TextInputLayout outlined using style="@style/Widget.MaterialComponents.TextInputLayout.OutlinedBox", the box looks almost the same, but the underline is gone. In order to remove the stroke just set the app:boxStrokeColor attribute to @null.

app:boxBackgroundMode="none" in parent TextInputLayout

If you want to use the filled box then below code perfectly work for me.

app:boxStrokeWidth="0dp"
app:boxStrokeWidthFocused="0dp"

add above lines in the input layout.