how on earth do i remove the removeable liners from ds's mammoth crocs?????

[ClareVoiant]

he's just peed in them! i thought they just popped off, but i cant seem to get them off,any help appreciated please.
TIA

the two buttons with the croc on at each side are holding the liner in just pop the the liner off they are quite stiff the liner has a button hole in it it is easier to pull the liner out of the shoe first

thanks lancarra, i thought they were poppers, not bottons. durr.... sorted now, thanks.