That's an excellent and very practical question! The answer is: it depends entirely on the specific design and manufacturer of your outdoor bench. There is no one-size-fits-all answer, but generally, benches fall into a few categories.
Some outdoor benches feature permanently fixed armrests. These are typically welded as part of a metal frame or are an integral, structural part of a solid wood or concrete bench. Attempting to remove these would likely damage the bench or compromise its stability. For these models, the armrests are a permanent fixture.
However, many modern benches are designed with modularity or flexibility in mind. It's increasingly common to find models where the armrests are attached with bolts, screws, or locking pins. In these cases, yes, you can usually remove the armrests with basic tools like an Allen key or a wrench. This is often done to save space when storing the bench for winter, to create a cleaner, armless look, or to make it easier to fit more people on the seating surface.
Before you attempt anything, the most crucial step is to check the manufacturer's instructions or product specifications. Look for terms like "modular," "removable arms," or "tool-free assembly." If you no longer have the manual, inspect the connection point where the armrest meets the seat or back. Look for visible bolts, caps covering screws, or a locking mechanism.
If they are removable, simply use the correct tool to unscrew the fasteners carefully. Store all parts safely together for potential reinstallation. If they seem fixed, it's best not to force them. For a permanent bench where you desire armless seating, your best option may be to consider a new bench designed specifically without armrests.
Ultimately, while not universal, the ability to remove armrests is a popular feature that adds versatility to your outdoor living space. Always prioritize checking your bench's specific design to ensure a safe and non-damaging modification.