Iv'e suggested this previously and it was rejected but I'm going to submit it again because it's only common sense.

I'm sitting here once again deleting hundreds of submissions one page at a time. All the other forms allow me to clear them down with just a couple of clicks. This form requires many clicks and selections and also constant scrolling left and right each time due to the way the submissions are listed, forcing the buttons off the screen.

It's all just a massive usability pain. It just needs a button and an alert to delete them all.

Thanks
Rob