Dear Aunt Hill,
Is there a way to "deactivate" a narcissist you live with?
It is impossible to ignore a person you live with without causing disruption and trauma to other members of the household. In fact, it's an absurd approach. However, you can ignore narcissistic behaviour.
To do this, you have to build yourself a construct that you can happily live within. For example, "I have to live with this person I hate" is a construct that will make anyone experience negative feelings all the time. Conversely, "I live with a mentally retarded person who doesn't realize what s/he's doing" can ultimately make you feel pretty good about yourself.
Remember, you cannot change others, but you can change yourself.
Best of luck!