The Red Devils have been lambasted for their decision to offload Scott McTominay to Napoli.
The midfielder has made a fine start to life at the Serie A club under Antonio Conte.
In a recent interview with Il Mattino, Di Canio said: "I would go to Manchester United to arrest all the directors – how can you give away McTominay?"
On McTominay’s summer departure, coach Erik ten Hag had stated: "It is a little bit mixed, I am very happy for him but it is mixed because I wouldn’t prefer to lose him.
"He is Manchester United in everything, he was so important for Manchester United.
"He was here for over 22 years but unfortunately it is the rules.
"Homegrown players bring more value and that is not the right thing to do but for everyone, for all parts, it is a good deal. Scott is happy with it, and Napoli and us."