You can reduce the amount of oil or fat you cook with, but if you are not prepared to do that then you should be disposing of it thoughtfully. You can consider reusing or repurposing the fat. Some people make bird feeders from the fat. Check with your local council for their preferred disposal method. If disposing of the fat through your general waste system you can follow this method: Let the fat cool so you are not handling hot liquid. Scrap the fat into a jar. Wipe the cooking tray with a paper towel and scrap further if needed. Add the paper to the scrapings in the jar. Add to rubbish. Wash the tray. Keeping a separate brush for oily or greasy items means your regular brush will last longer and water will not be oily when you go to use the regular brush.