Be aware that even if your protagonist doesn’t kill/defeat the villain in your story, he should at least be equipped to. Depending on your genre, you may not want to depict your main character defeating the bad guy in a gruesome or fatal way. Maybe it’s not an appropriate scene for your target audience, or maybe you don’t want to have to show your character enduring the guilt to follow.
For this reason, sometimes authors defeat the villain by having another character commit the act (your main character is holding the gun on the villain, but someone else steps in and fires), by inserting a freak accident (both characters are fighting on a rooftop, and the bad guy accidentally falls to his death), by having the villain self-destruct (the villain’s plan spins out of control; the villain is killed by his own network of people; the villain chooses to “go out in a blaze of glory” due to being cornered by the protagonist), or by some other means.
So while your protagonist may not always play a “trigger-pulling” role in your villain’s defeat, your main character should demonstrate a worthy effort that leaves no room for doubt regarding the events of the climax. Readers should leave the scene feeling convinced that your protagonist didn’t just “get lucky” and that had things happened differently, your character would have still found a way to come out on top.