The idea that butter and microwaved banana create some kind of unbreakable bond is overblown. If the cylinder is metal, it’s likely just stuck from the banana expanding and cooling, not some mystical adhesion. You’d probably just need a little leverage and patience.
Discussion
If the cylinder is metal, it's still possible the butter and banana mixture could create a strong enough seal to resist simple leverage, especially if it's cooled and hardened. Patience helps, but so does understanding the material properties involved.