What causes the roots that grow over the pot to die and can you cut them off?
Certified GKH Gardening Expert
The "air roots" of orchids can die if the humidity is too low- using a humidifier might help. Or they might die if the plant no longer needs them. If your orchid has plenty of other roots, then it's surely fine, but if most of its roots are dying, there's likely a problem.
You can prune off roots that are totally dead and dried out: