I find that the scouring side of a blue ("non-scratch") kitchen sponge, with water and dish detergent and lots of elbow grease, is effective, but it does require lots of elbow grease and I'm wondering if there's an easier way.
Deglazing is the easy way that I've found over the years:
- Unplug the grill, but don't give it a chance to cool down.
- Drip water along the top edge of the grill (squeeze from a sponge, or a soaked paper towel).
- You should see the water turn murky brown as the stuff releases ... if it doesn't, add more water.
- After 20-30 seconds or so, wipe it down.
It's a bit more difficult to clean the top ... you have to learn it back. You can also wipe it down with a soaking wet paper towel.
You might have to scrub a little bit, but the water should get off the majority of the gunk. Beware that you'll tear up paper towels on the little nubs at the bottom edge of the lower part ... I typically save that area for last, as anything to clean above it would drip back down there anyway.
Also, if the grill cools off too much, you might need to let it re-warm some.
For me, I find the best way to clean it is, with the grill still on, get a big piece of paper towel, wet it very well, put it on the grill, and close the lid for a few seconds. Lift the lid, relocate the paper towel using a pair of tongs, close the lid. Repeat until all is clean, letting the steam do all the work. The worst will be cleaned and easily removed with another piece of paper towel.
Whenever practically possible, wrap your food in aluminium/kitchen foil. It will prevent a lot of cleaning later on. And it will preserve all the flavors and juices.
And as others have suggested, I find it easy to clean with a piece of dry or wet tissue and then water while it is still warm.
Personally I clean it while it's turned on. I used to work in a kitchen and this is how we always cleaned the more industrial versions.
The surface is non stick anyway so shouldn't be too difficult to clean. Just take a cloth or green/yellow scouring sponge heavily soaked in water and give a scrub on the top and bottom.