The Spurs forward hasn't scored in five Premier League appearances after a tumultuous summer of transfer speculation.
He has scored six goals in total this campaign, across the Europa Conference League and the EFL Cup, but his top-flight performances have been seriously underwhelming.
The player claimed he was committed to Tottenham once his hopes of a move to Man City were dashed late on in the transfer window.
The 1966 World Cup winner believes, though, that Kane deserves to play in the Champions League and keeping him in N17 against his will is doing neither part any favours.
He told the Warm Up: "To be honest with you, I get on with the Spurs players, we were great pals years ago. The thing I would say about the Spurs situation quite clearly - they should let Harry Kane go.
"Keeping a player who wants to move on, and maybe deserves an opportunity playing in the Champions League.
"Keeping him there with resistance is not necessarily good for the player and not necessarily good for the club.
"I think they should move him on, personally.
"Let's get this right, I'm not being detrimental about to Spurs or the club. They are a fantastic club and I'm great pals with the players from years ago.
"I never go along with this Spurs-West Ham antagonistic attitude. I never went along with that.
"I'm saying it purely as an outsider looking at the player and the club.
"The club is great. They have a great ground. He's a fantastic player but I think the time is to move on and progress. It's my humble opinion about this situation."
And Ramon Vega, who won the League Cup with Tottenham, believes Kane's action in the summer were disrespectful to all parties, including the player himself.
He told the Weekend Sports Breakfast: "There is no doubt whatsover about disrespecting the club, especially the fans, but also himself in terms of how he handled that situation, as a captain of England to start with, as he represents the country.
"There is doubt, if a player in the dressing room wants to leave it's a very awkward kind of situation because the other players think, 'is he staying or not, or does he even care about staying?'."