For the Can-Am Outlander ATV, you’ll find the battery under the seat. You’ll need to remove that. You’ll see a battery safety clip held in by three screws. Take your 10 mm socket, remove those screws and set the battery holder aside.
For the Can-Am Defender SSV, the battery is located under the passenger seat. Flip the seat up and remove the toolbox if you have one. You’ll see an access panel. There’s a groove for your hand to simply pull the panel off. The battery is held in place by a battery holder with two 10 mm bolts that you can quickly remove. Note: for Defender PRO models, the battery is located in the cargo storage box on the passenger side.