John Gill says he was left with no other choice but to leave Dundalk.
The former assistant coach at Oriel Park was left in charge of first-team affairs - along with Alan Reynolds - following the departure of Vinny Perth.
The obscure Italian coach Filippo Giovagnoli is set to take over at Dundalk.
The club have provisionally called a press conference for Wednesday afternoon, where it's expected Giovagnoli will be unveiled.
The Italian formerly oversaw summer camps at AC Milan, and most recently has been director of coaching at the New York City FC-affiliated Metropolitan Oval Academy.
Gill's departure ends a long association with Dundalk.
Today I left @DundalkFC. I felt I had no choice given recent events. I am extremely sad it has come to this. I wish the clubs staff, players & fans every success in the future
— Giller (@JGill_Giller) August 25, 2020
He was manager when the club were promoted to the Premier Division in 2008.
Gill was brought on board at Oriel Park in 2018 following the departure of Stephen Kenny, and the need of a Pro License-qualified coach to work alongside Perth.
He says he had "no choice" but to leave, given recent events.
Gill added, "I am extremely sad it has come to this. I wish the clubs staff, players & fans every success in the future."
The departure of a well-respected figure like Gill will heap more pressure on club owners Peak6 to explain their vision.
Following his departure, Perth said, "There's been things in the background that just haven't been good enough, and ultimately they've come onto the pitch."
Rumours there was interference in team selection persist.
The former head coach added, "There's no doubt there was difference of opinion with the board, there's no doubt about it."