The former Brazil international only signed a new deal with the Brasileiro Serie A side in January of this year - despite interest from Besiktas.
However, Ronaldinho and Atletico have now terminated the attacker's contract by mutual consent, with the former Ballon d'Or winner expected to announce his next destination at a press conference on Wednesday.
"I can't call on Ronaldinho anymore," Culpi told SporTV on Tuesday. "His cycle with us has ended.
"It's unfortunate because he's an idol to all of us. Everyone loves his football, the way he plays and he's a very charismatic person.
"But that's the way it goes. He's leaving and we must move on without him."
Ronaldinho joined Atletico in June 2012 after parting company with Flamengo and inspired the club to a first Copa Libertadores triumph the following year.
However, he is now being linked with a move to Boca Juniors, who are looking for a replacement for iconic No.10 Juan Roman Riquelme, though Fluminense and an as yet unidentified MLS side are also said to be interested in acquiring the ex-Barcelona star.