Remove the lid;
Observe the manner in which the internal parts are installed because you'll have to reinstall it properly when you finish cleaning the trap.
Examine the gasket for damage - never use tube silicone as a gasket.
If the gasket is falling into the trap, clean and reattach it to the trap;
Begin dipping (or vacuuming) the waste from the trap.
Remove all contents until unit is empty.
No need to use degreasers or soap and water - no one is eating out of this trap.
Make sure the trap has been properly reassembled (all internal parts are in place).
Tie up the bag of waste (that has the oil dry soaking up the liquid) and place in the garbage (solid waste) dumpster.