Proving we are not in a simulation and proving that we are in a simulation are two different things. It is also possible to be in a simulation and not in a simulation at the same time.
To prove that we are in a simulation means to prove there is something incoherent or misaligned about the reality being experienced, versus the reality known to the system.
In a social context we can detect foreign or simulated social situations by verifying it against what we know. This is no different from trying to prove mathematically sound physical simulations of the world.
Since we cannot sense beyond our own senses, without superhuman ability, we cannot prove the existence of what is outside us.
So, Mr. Elon Musk, prove to me you are super human. Prove to me that we are living in a simulation as you so boldly claim.
I meant to say prove physical hard reality simulation-not social reality simulation. You may find it quite difficult or near-impossible.