  If entanglement builds spacetime, then conversely, disentanglement ought to
destroy spacetime. From the quantum null energy condition and quantum focusing
conjecture, we obtain disentanglement criteria which necessitate infinite
energies and strong spacetime singularities. We apply our results to the strong
cosmic censorship proposal, where strong singularities at the Cauchy horizons
in black holes are desirable. Using our disentanglement criteria and without
resorting to any detailed calculations, we provide an exceedingly general and
physically transparent discussion of strong cosmic censorship in semiclassical
black holes. We argue that strong cosmic censorship is enforced in
asymptotically flat and de Sitter black holes by disentanglement and describe
how similar disentanglement might be avoided in some anti-de Sitter cases.
