Arocca told North chairman James Brayshaw of his decision in a meeting on Tuesday morning.
Arocca did not attend a press conference at Aegis Park to announce his decision, but tendered a written statement that Brayshaw read.
"As a result of matters beyond my control I have handed in my resignation to James Brayshaw effective immediately," Arocca wrote.
Brayshaw said a report in The Australian on Tuesday, which stated Arocca was set to resign because of the North board's reluctance to extend his contract, had been the "touch point" for his decision to resign.
"To put it bluntly, he said, 'I consider my position untenable and I'm resigning'," Brayshaw said of his meeting with Arocca.
Brayshaw said he had not been aware Arocca had been unhappy in his role before Tuesday, but had not tried to talk him out of his decision to resign.
Brayshaw said North's board had met last month and had established the process by which it would decide whether to extend Arocca's contract, which expired in October, or whether to pursue a new candidate.
Brayshaw said Arocca had been informed of this process and, contrary to The Australian report, had not demanded an answer by a specified deadline.
Brayshaw also denied Arocca had fallen out with him and North football manager Donald McDonald.
"To be absolutely honest, in footy clubs you regularly get times where people don't see eye to eye," Brayshaw said.
"It's a robust environment. I think Donald and Eugene have great respect for each other. I'd be lying if I said they always saw eye to eye, the same way I'd be lying if I said that Eugene and I always saw eye to eye.
"It's a brutal industry and there are times when you do have to have very frank discussions with people."
The North chairman said he retained full faith in coach Brad Scott and McDonald.
North chief operations manager Cameron Vaile will act as interim CEO while the club searches for Arocca's replacement, Brayshaw said.
Under the management of Arocca, who joined the Kangaroos from Collingwood where he had been in charge of that club's commercial operations, North Melbourne moved into a state-of-the-art training and administrative facility at its Arden Street home and eradicated some of the club's long-term debt.
He and Brayshaw oversaw North's deal to play two home games each year from this season at Hobart's Blundstone Arena.
Brayshaw said: "In any way you care to measure it, Eugene's impact on our club has been profound."
More to follow...
