private static final Set<Integer> blocks = Sets.newHashSet(); //pre-prepared list of the blocks in their 'combined' version.

public void method(Player p, Region region) {

    World world = FaweAPI.getWorld(p.getWorld().getName());

    EditSession editSession = new EditSessionBuilder(world)
            .fastmode(true)
            .allowedRegionsEverywhere()
            .limitUnlimited()
            .build();

    for (Vector pt : new FastIterator(region, editSession)) { //found in the documentation.
        BaseBlock block = editSession.getBlock(pt);
        if (blocks.contains(block.getCombined())) {
            block.setCombined(0);
        }
    }

    editSession.flushQueue();
}