2007 Honda Civic - Removing sub box?

I have a 2007 Honda Civic EX coupe and the subwoofer in the back rattles. I know I can just disconnect it but I want to take it out and there is something like a guard right under it and I’m not sure how to take it out. There are these white screws that are really hard to take out because their the kind of screws that you hammer in and once they go in, they expand on the other side. I think I would have to squeeze the other side of those screws with pliers but there isn’t enough room to fit pliers. So how do I take it out?