Question: How did The Green Goblin get captured and sent to Ravencroft after he killed Gwen?
Question: Who is in charge of Oscorp now?
Answer: Donald Menken, the Vice President of Oscorp, framed Harry for covering up Max Dillon's accident and has him removed so he could take over the company. By the end of the movie, Oscorp would now be under his control.
But he was killed in a deleted scene.
Deleted scenes don't make for canon content - it has to involve a degree of guesswork. Some deleted scenes happen, we just didn't see them in the movie, others are movie ideas that were cut out precisely because they don't fit the movie as released, so didn't happen. No way to know which is which, and this is just a thought exercise anyway.
So this is possible that, at the end of this movie, Menken is still alive, right?
He is very much alive. I saw the deleted scene where he was killed, and this scene contained a lot of bad CGI, so it's definitely not canon.
Answer: Peter could have webbed him up and called the police anonymously.
MasterOfAll
Very likely. However, there was a deleted scene in which Peter, out of anger over Gwen's death, almost beats Harry to death.
Yes. We also see Goblin getting knocked out when all hell breaks loose, and the gears all break apart. Chances are, Peter just webbed him up. (Although, as the other response says, he also got beaten up in a deleted scene.)
TedStixon
My theory is that Harry regained consciousness and started taunting Peter about Gwen's death. As a result, Peter flew into an uncontrollable rage and started savagely beating Harry, almost killing him. He stopped very short of killing him, webbed him up and called the police anonymously. It all happened off-screen.
That's a nice theory and totally plausible, though I don't know that this comment is strictly necessary. It's basically just restating what other people have already said, but in excessive detail.
TedStixon