How can I take my mother off of the property deed now that she is deceased? The deed has myself, my sister and my mother on it.

If you were all joint tenants, then you can record an affidavit of death of joint tenant with a certified copy of the death certificate and a preliminary change of ownership report to remove your mother from title. However, if you were tenants in common, then you would need some type of probate action, depending on the value of your mother's interest in the property.  If the vesting doesn't specify, then California law presumes that you were tenants in common.