On Android 6.0:
1st way:
Step 1:
First, we access the link Settings> Applications> Application Management.
Step 2:
Next, select More> Applications may appear on the top. A list of applications appears, you just need to turn off all applications in this list, by swiping the bar to the left to disable the screen overlay feature on Android.
2nd way:
Step 1:
First, you need to access the Settings on the device and select Apps. Next, click the gear icon in the right corner of the screen.
Step 2:
In the new interface, scroll down and select the item Special Access. Next, select Draw on other applications. Some devices will immediately display this option when we click the settings icon.
Step 3:
In the list opened, we will select the applications that we want to license then disable the feature Draw on other applications (Permit drawing over other apps)
Good luck!