I have alot of dendrobiums in which the flowers have all fallen off and died, but I am familiar with cutting Phals spikes down when the flowers die off, but do you cut the dendrobium the same way?
Yup, you do, only a couple kinds of orchids will regrow on the same spike, dendrobiums are not one of these.
Please correct me if I'm wrong, I don't know everything but I have a dendrobium and I looked around a lot to find the answer to that and I was told that it's ok to cut them, they won't regrow on an old spike.
You can cut the spike off yes. But do not cut the cane, incase there is some confusion what is a spike and what is a cane. You probably already know this but just making sure.