No one is a “former” Catholic. Once baptized a Catholic, a person is always a Catholic.
So this could read
New L.A. Episcopal Bishop’s Historic Journey [Woman, Roman Catholic]
Isn’t there something called self-excommunication?
She's "defected from the faith by a formal act," to use the phrase in Canon Law.
However, unless she's in an irregular marriage, she could certainly come back by making a good confession. Of course, she'd have to renounce all her offices and her membership in her non-Catholic ecclesial community.