Way to remove the front grille without removing bumper?
 

I'd like to be able to access inside the bumper to check my oil cooler without removing the bumper. Is there a way to disconnect the grille or attach the grille in a manner that allows easy removal?

No. I'm 99% sure it's all molded as one piece. I researched because I'm planning on cutting the "mouthpiece" off of the front of my BRZ when it goes in for mods, and everyone says it's one piece. There's even a thread where a guy does just that and cuts his off like I intend to do. If it came off any other way I'm sure he would have done that before cutting it out.

100% it's all one piece, I just took mine off last night. I ended up taking the passenger fog light out to aid air flow to my cooler

No, it isn't one piece. It clips on to the bumper. You should be able to push it in towards the rad with some force and pop it out.
EDIT* http://www.grillcraft.com/installs/i...install_id=309


Picture #18 shows how to remove it.

I think it's different for the FR-S though. You guys have a BRZ but OP has an FR-S.
I thought the FR-S grill was removable, but I haven't tried it, though I actually need to do this as well for a different reason. :iono:

it is absolutely removable on the FRS. I had a nice chat with the manager of a car wash after I noticed mine was pushed in after a wash.