The sump plug is located on the base of the engine. It is accessed underneath the car
Don't forget to have a suitably sized receiving tray in place
With an oil catchment tray in position, use a 12mm Allen key or socket to carefully remove the sump plug and fully drain the oil.
When the sump has emptied, wipe clean the sump plug area with a paper towel and refit the sump plug and washer
Replace (new) sump plug and washer. Do not over tighten