A medically supervised detox is safer than an DIY initiative. Having said this, the liklihood of a life threatening complication from a DIY heroin detox is substantially less than the risks of continued use.
Is she also detoxing from alcohol?
As you know, detox is not recovery. Whether or not to seek help/support is her business.
"Needing to"....is an attempt to please other people.
"Wanting" is what it takes to get and stay clean for oneself.