First question:How to remove shadow of a button?
Here is the answer:
Just add this attribute to your button
android:stateListAnimator="@null"
Second question: How to make the corner of button sharp without losing the standard ripple effect.
Here is the answer: But first you have to make two drawble file with same name but one for below api 21 and one for api > 21 because the ripple is only available only api > 21.So now I am showing how to create that.Read the following text carefully
Right click on the drawble folder and choose new and "Drawble resource file" and hit next then name the drawble whatever you like and press ok.Then again right click on the drawble folder and choose new and "Drawble resource file" and hit next and name the drawble exactly what you named the previous drawble folder but this time at the bottom you can see a section called "available qualifiers".Go to this section and at the very bottom you can see "Version",click it and then you can see a arrow icon at the right,click it then in the "Platform api level" add 21 and then press ok.And now if you expand drawble folder you can see two file of your created drawble file.Once for api that is below 21 and once for upper 21.Open drawble file that you have created and make sure you open that have "(v21)" at the last.Now delete everything from there and add the following code
<?xml version="1.0" encoding="utf-8"?>
<ripple android:color="?attr/colorControlHighlight" xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape>
<corners android:radius="0dp"/>
<solid android:color="#D6D7D7"/>
</shape>
</item>
</ripple>
And add this attribute to your button
android:background="@drawable/youdrawblefilethatyouhavecreated"
And now if you run your application you can see that there is no shadow and your button has sharp corner and if you click the ripple shows up.
Lastly,your button look something like this
<android.support.v7.widget.AppCompatButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="New Button 1"
android:background="@drawable/yourcreatddrawblefile"
android:stateListAnimator="@null"/>
Hope this help!