The former Tottenham and Everton midfielder's deal with Como was to run to the end of this season.
But after failing to convince Como coach Cesc Fabregas in preseason training, Alli was frozen out from first team training ahead of being released yesterday.
A joint statement from club and player was made today, saying: "Como 1907 and Dele Alli have agreed to a mutually agreed termination of their contract.
"Dele is eager to have regular playing opportunities, and since he was not part of the club's immediate plans, both parties felt it was the right decision to part ways before the transfer window closed. The club thanks Dele for his time at Como and wishes him all the best for the future."