Why there is <- Back button on top of tool bar in Android

1. How do I get rid of the back arrow on my Android Toolbar?
2. What does the back button do on Android?

How do I get rid of the back arrow on my Android Toolbar?

setDisplayShowHomeEnabled(false); //disable back button getActionBar(). setHomeButtonEnabled(false); In a older android phone, the back button is removed with these two code lines.

What does the back button do on Android?

The Back button appears in the system navigation bar at the bottom of the screen and is used to navigate in reverse-chronological order through the history of screens the user has recently worked with.