You used to be able to opt-out, but not anymore:
1) opt out with the DMA (note: there used to be an opt-out form at http://www.dmachoice.org/eddm but it no longer exists)
2) each local advertiser has to download the list for your area of opted-out addresses and print them on a facing slip before handing their bulk flyers over to the USPS
3) the USPS has to pass that on to the mail carrier
4) mail carrier has to check the list before putting the (unaddressed) flyers in each mailbox
So many points of failure that you just know it was designed so that the opt-out would not be honored. Then they stopped pretending entirely by removing the form to opt-out a few years ago.