If a person dies, how to cancel phone and services?
Grieve first. I'm sorry for your loss.
Nobody can sue the dead, let it go even if they go to collections.
Once you have reasonably grieved , you may need to research sending a copy of the death certificate to Verizon. But seriously, do not worry.
Now, if you have a combined account and the one you lost was the primary person, that's another subject.