Nuno was sacked by Forest on Tuesday morning before being replaced by Ange Postecoglou.
Collymore admits he's also been left unimpressed how former Tottenham boss Postecoglou was handed the job.
He told Tribalfootball.com: "So as a pundit, I think it's nothing short of a disgrace. Lots of people like me,
when they saw (owner Evangelos) Marinakis on the pitch last season, said, oh, there's something wrong.
"Then fast forward to several weeks ago and you've got a situation whereby Nuno comes out in his press conference and very candidly says it's not good at the moment and then you have situations like Douglas Luiz coming in who apparently is one of Edu, the transfer guru's players, and he's not played a minute under Nuno.
"So obviously there's a power play. The manager's saying, I pick the players, you can buy who you like, but I'm going to choose whether they play or not. And Mr. Marinakis has got involved and said, enough is enough."
Lazy appointment
Moving onto Nuno's successor, Collymore branded the appointment as "lazy".
He continued: "Am I surprised that it's Ange? No. I think that it's actually a very lazy appointment because in the summertime, I saw a picture of Marinakis handing over a bit because I think that Ange was the first manager of Greek origin to win a European trophy.
"And Marinakis gave Ange this trophy in Athens. And I thought then he's going to be chatting to him and they'll be getting on and they'll be speaking Greek together. Yada, yada, yada. And so from that perspective, it fits as well.
"You know, Greek guy gives a Greek guy a job. Ange, yes, won the Europa League with Spurs. Nottingham Forest are in the Europa League this season. Marinakis is thinking, well, if he can win it with Spurs, he can win it with us.
"But the most important thing is, is that how is this going to affect Nottingham Forest? Well, Ange Postacoglou's style is the polar opposite of Nuno's.
"Nuno at Wolves and Nuno at Forest sat deep, absorbed lots of possession, hit on the counter-attack with (Anthony) Elanga last season.
"Ange's ideal scenario is defend at the halfway line and we go after teams. Well, that's fine. But to be able to do it and translate one system into another in the very early stages of a new season is going to be very difficult.
"So it's just going to be fascinating to see how that develops, but overall in terms of my gut feeling it's just very, very poor
the way that the club, the owner has treated Nuno Espirito Santo who's been a very good manager for Nottingham Forest."
- Stan Collymore was speaking to Tribalfootball on behalf of NewBettingSites.uk