The first thing to do is read the manual or visit the manufacturer’s website. That said, here is the Heloise hint, and I just did this! If it’s a greasy buildup, all you need is a little ammonia and paper towels. Put the towel on the grid (UNPLUG the iron), then pour on about a teaspoon of ammonia and let sit a few hours. Keep away from pets and children! Use a plastic brush or scrubbie with a drop of dish soap and scrub away!
Heloise hint: Do not spray oil on a hot waffle iron! Use only while the iron is cool, so it will heat up as the iron heats up. This prevents the sticky residue from building up on the iron. – Heloise
P.S.: I also use the “slim” sticky as bookmarks for things I want to go back to while I’m reading. I may even note on the paper what the idea or information is.