With the griddle still on and hot from cooking, use a metal scraper and high heat BBQ gloves to apply a little pressure and scrape everything on the griddle surface from the front towards the back grease catch. If the surface is uneven, grease may pool in the corners and along the edges. Run the scraper along the edges and in the corners to pull the grease toward the center before guiding it to the grease catch.
Take a folded up paper towel with some metal tongs and wipe up any other bits of food and oil, making sure to get into the corners thoroughly.
If you have spots that are not coming off with the scraper, squeeze a little bit of water on the spot to help steam it off.
Drizzle a high smoke point oil, such as grapeseed oil, across the surface of the griddle.
Using paper towels held with tongs, wipe the oil across the surface to form an even layer. The paper towels can be discarded in a small metal bucket to avoid melting a trash bag.
Allow the oil to smoke off for a few minutes until the smoke dissipates. Turn the griddle off and let it cool down.
When the griddle is completely cool, cover the surface with a silicone cover, then the hard top cover, followed by a soft cover over the entire griddle.