That's ASUS new way of grounding the IO plate to the motherboard, do not remove it!
Make sure the I/O plate is secured into the case opening, and make sure the motherboard is aligning with the mounting studs on the M/B mounting plate, then push the M/B into the I/O plate foam until your M/B screw holes align with the mounting studs, then secure it with screws but do not tighten until all the screws are in place, and then tighten the screws SNUG but do not gorilla tighten then! (Do Not over tighten them)
Usually before I tighten the M/B mounting screws I note the screw alignment heads with the grounding solder they tighten against, and push or pull the motherboard until they line up perfectly, then snug them all down.