If you look at the Sydney Opera House website:
"Although Utzon had spectacular plans for the interior of the completed shells he was unable to realise this part of his design. In mid 1965 a new Liberal government was elected in the State of NSW. The Minster of Works Davis Hughes began questioning Utzon’s designs, schedules and cost estimates and eventually stopped payments to Utzon who was forced to withdraw as chief architect in February 1966.
Following Utzon’s letter of resignation there were protests and marches through the streets of Sydney led by Australian architect Harry Seidler, author Patrick White and others, demanding Utzon be reinstated as architect. The NSW government did not offer him this role, Jørn Utzon left the country at the end of April 1966 with his family, never to return to see his masterpiece again."
So if you resign because they quit paying you, I think most of us would say it was closer to being fired.