The sun and gravity should bring them down on their own. You can put a dab of roofing cement under each tab for extra insurance.
When you see things like that it's usually the guy who did the roofing saved himself about 15 minutes on the whole roof. The tabs are supposed to be cut off of the very first course of shingles at the eaves. That places the adhesive on the top of the shingle at the bottom edge of the roof to glue down the lower edge of each tab on the first exposed course of shingles.
If that fifteen minutes would've killed him, he could've bought a roll of the starter strip that serves the same function.
R