I was wondering if it is possible to record NO SOUND while filming
with the Canon XLS-1?

I'm not sure if there is a way to make it have no audio when filming a scene.

Thanks for your time,

Todd

un-plug the mic.

Yup, that'll do it.

An then select manual gain, line level, and turn the gain to zero to minimize the residual noise floor in the recorded audio tracks. (They should be around -72 dB or lower relative to max digital record level)

Of course you can delete or mute the sound in post.

There are a lot of simple suggestions already presented, but why/what adavantage is there to do this??

Ours is not to reason why, ours is to answer Todd's question.

Whether or not this is a good solution to his situation is a separate matter altogether.