Go into the trash/deleted folder
Press the Menu button
Select Delete All
What did not work? Which step do you not see?
The Menu button is a physical button on your phone. Are you accessing AOL emails through the email program on your phone or by using the browser?
Great -- Please go into the deleted folder and press the Menu button on your phone and select Delete All
Tap and hold the back button to get the menu options
Go into your Deleted folder
Tap and hold down the back button to see the menu option
If that option did not work then you will need to use an email app such as K9 to delete the emails at once instead of the built-in email program on the S6.