The sump plug is located on the base of the engine, and is accessed underneath the car, so remove the undertray
Undo the undertray fixings
Do not forget to have a suitably sized receiving tray in place
With an oil catchment tray in position, use a 19mm spanner or socket to carefully remove the sump plug. Fully drain the oil.
When the sump has emptied, wipe clean the sump plug area with a paper towel
Replace (new) sump plug and washer. Do not over tighten