The resignation of Limestone Coast Local Government Association executive officer Adrian Maywald takes effect on Thursday.
He had spent six months in the role.
LCLGA president and Mount Gambier Mayor Lynette Martin said the board had accepted the resignation.
“The LCLGA Board thanks Mr Maywald for his service and wishes him success in his future endeavours,” Mayor Martin said.
Mr Maywald was the Lucindale Area School principal for 11 years before leaving last year to head up the Limestone Coast Sporting Academy.