Sledgehammer? Do I need to make any cuts first? Also, where's a good place to put the tow hook after they're gone?

Sledgehammer? Hope you are persistant. There are 4 pieces of fairly big gauge metal there and cutting is the only option. I have a different style tow hook and just moved it up the the next available bolt hole at the top and drilled a new hole for the bottom location. Yours could probably be used, but hard to tell by just looking. You will lose the bottom bolt hole unless you get creative when cutting.

Sawzall or oxy torch is how we do them. Sawzall should take around 2-3 minutes per side - the metal there is thick.

Look on keith's targa build, he showed what to cut out and then used a strap style tow loop through a big hole in the bumper IIRC.