Removing icon (triangle with exclamation mark)

[AC Question]

Recently I tried to send an email with photos. Apparently, the file was too big and could not send, so I deleted it. But I get an icon, a triangle with an exclamation mark, at the top of the screen. I scroll down and it said "couldn't send attachment." When I tap on that it send me to my gmail outbox, which is empty. Can anyone tell me how to get rid of the icon?

 

[B. Diddy]

Welcome to Android Central! When you swipe down the Notification Shade, can you swipe that notification away? Or tap the clear all notifications button?

 

[farrah waterfall]

I'm having same issue just got the phone yesterday and it won't come off. So it's not data usage