which of these verbs is correct?
so that the meaning is to reduce stress or stress free
"Relieve stress" is an older, more mainstream term. Anything that reduces stress -- medicine, diet, exercise, laughter -- is said to relieve stress.
"Release stress" is more of a self-help, new-age term. It's commonly used by people who practice yoga, meditation, and guided imagery. Most often, it refers to reducing stress through relaxation and, occasionally, homeopathic (herbal) remedies.
Lots of luck,