'completely detached' is a correct and usable phrase in written English.
It is often used to describe someone's emotional detachment from a situation, as in "She remained completely detached from the argument."
I felt completely detached.
Because in my own life I'm sometimes completely detached from it as well.
"Fuleco is completely detached from the conservation of his species or his habitat," laments Melo.
It's a debate between reality and someone who is completely detached from reality.
"They're not completely detached from it," he said, "because it's part of who we are.
Four shuttle missions have ended with tiles completely detached; every mission ends with some damage to tiles.
It's a big painting, rather formal, about the materiality and physicality of close, but completely detached observation.
In many crime novels, the events seem completely detached from the economic, political and social context in which they occur.
Within this community, the Internet is treated as a venue for bombastic Trumpian fantasy, completely detached from the real world.
"This buyout is the perfect evidence of how they have lost touch and they are completely detached from the marketplace".
She should not be so independent that she is completely detached from the court of public opinion.
