I wouldn't mess with it. I've pulled one of those off before and part of the label came off with it. Even if the sticker comes off completely, you are still going to have a residue on the disc. I'm guessing you want to keep it? If you just want to play it, you can beat it in less than 8 hours from what I've heard and then you can return it.
If the OP does mess with it...here is the method I've used to remove such labels. Take a straight rectangular razor blade (as opposed to the utility knife parallelogram ones), and extremely slowly and carefully, angle the blade at maybe 20 degrees or so to the disc, and little by little work the label off. Also, putting a little Goo Gone on the blade tip every little while helps as well. Once the label is completely removed, you can use Goo Gone to clean any label residue.
BTW, I stopped at the 5 nearest (within 30 miles) Gamestops the last two days that were listed as having Ico in stock. Came away with only 2 copies, one complete black label and excellent condition disc, and one disc only copy that was slightly scratched. It really pisses me off that the God damn inventory tracking system is so fucked up, I mean three stores that still have it as ghost inventory? And it's not like someone bought them right before I did, the people at these stores tell me "oh, you're like the 50th person to ask about it in the last couple of weeks, har har har..." They are still listed on the inventory page for the game.
And of course Ico is one of those games that, because of its value, you don't want to call ahead and give the employees at a particular store the head's up that they could have treasure in their store. They will more often than not steal it right out from under you.