Hi guys , today the crank is arrived. there is a little problem , i can't remove the chainrings.... in the crank there is a piece very similar to those crankset bolts (5mm hexagonal) but from a close view they are more similar as rivets...
Can i replace with normal 5mm hexagonal? but first ... how i can remove them? tnx!

img there https://imgur.com/aRbQcDG