If exposed to undiluted oil, use coconut, olive or another edible oil to cleanse the skin. Using oil will calm the burn and assist to remove excess essential oil from the area.
Using any cooking oil, repeatedly wipe the affected area (wipe off and apply more oil as necessary to fully remove from skin).
Or wash the area with cool soap and water, wiping and repeating as needed to remove all essential oil from the skin.
*Never use hot water to wash oregano essential oil from the skin, only cold or cool soapy water. Using hot water will cause/increase the burning sensation on the skin.