To remove the plastic piece you have to take out the two bolts in the top left of your picture, two 10mm on each side. Then remove 3 or 4 of these type of clips from inside the grill area
And there may be 3 or 4 more inside the bumper mouth on the top. But now that I am thinking about it, I don't think those will have to come off for a chrome bumper..
If you are talking about the flat looking clips under the head lights, don't try to remove those. Once you have the bolts and other clips out, the trim will pull out of those. You don't want to/can't remove those.
I know its a lot of work, but its not that bad. But Tacoma's aren't much better; I have done a few before and you don't have to take off the bumper for theirs, just some small trim covering the bolts under each light. Which is nice, but I have broken every one of those trim pieces I have touched. They are just so fragile that it isn't even funny.