It means to stop being a tortoise; hence, detortoise

Since no one gave the serious answer yet: term used by philosophers Deleuze and Guattari

In critical theory, deterritorialization is the process by which a social relation, called a territory, has its current organization and context altered, mutated or destroyed.

In the meme it’s how the characters in these sorts of stories have become so alienated by capital that they need to resort to extreme violence to change their social relations (usually in a self-destructive way, because revolution is precluded by the material conditions in the imperial core in these narratives).