There is some silicone lube that does wash off, though not ALL do.
For Instance
I was simply answering her question about if there was one that is better for the female PH, which is what I was answering. She didn't ask anything about stay-ability (which I also think is a good thing, even with silicone lubes that don't wash off, because you don't have to reapply. Silicone lubes are also perfect for sex in water for that reason).
The silicone lubes that do not wash off will be eliminated by the body naturally. If she is using it vaginally, which is what she said, when she pees, it will leave her body.
I hope this is not taken as being argumentative, I'm just restating what I have learned in my personal research regarding lubricants.