I don't think we can, but if we did find out that we are, would the entity/entities that control the simulation pull the plug on it? Or would it/they be interested in what we do next?

Press Ctrl alt delete

We can't necessarily. It would all depend on the nature of the simulation. But we can use reasoning to determine that we're not in a simulation.

When our creator falls in love with us and creates a living copy and lets us out, or when you see a sign in your head that reads "uncaught exception".

If we lived in a simulation some nerd would have hacked it by now.

ask Jeeves

This IS a simulation, it's just like the Matrix, but our bodies are not needed for power, they are being used to pleasure xenomorphs , I'm sorry that this is how you learned