The broadcaster’s Canberra staff were informed of Greene’s decision on Monday in an email from bureau chief David Lipson.
“The ABC maintains the importance of upholding its editorial and other policies,” Lipson said in his email.
In June, the ABC said the allegations raised by Media Watch were serious, and that if proven, the behaviour would be “unacceptable and could constitute misconduct”.
Media Watch estimated the round trip to Germany on a business-class return ticket was worth around $16,000, which also included hotel stays in the cities of Hamburg and Kiel, paid for by the German company.
An ABC spokesperson confirmed Greene’s resignation on Tuesday morning.