Agree with Planto.
If you really want to truly test if it is still has some life there..try to make a slice at the lower end, if you do not see any fresh part there, then it is truly gone, I do not see any green at all in your cacti.
Typically you should see something like this when you slice it..kind of like a cucumber flesh, so it is still alive and salvageable, allowing the cut portion to dry and scab over, it will grow new roots there:
Otherwise, brittle and dry..dead cacti.
