The honest answer here has to push back against the question. OCD has a well-established treatment, and hypnosis is not it. Calling hypnosis a treatment for OCD would mislead someone toward the wrong door at a moment when the right door is known.
That right door is exposure and response prevention, usually shortened to ERP, a specific form of cognitive behavioral therapy. ERP works by having a person face the thoughts and situations that trigger their obsessions while resisting the compulsions that normally follow. Doing so, with support, gradually teaches the brain that the feared catastrophe does not arrive and the ritual is not needed. It is demanding work, and it is also the best-supported psychotherapy for OCD, with a large share of people improving. For some, a serotonin reuptake inhibitor prescribed by a doctor is added. These are the front-line answers.
Hypnosis stands well apart from that. There is little published evidence that it treats OCD, and the studies that exist are few and small. Nothing in the record supports the idea that focused relaxation reaches the obsessive-compulsive cycle the way exposure does. A claim that hypnosis can reframe obsessions or dissolve compulsions runs ahead of what anyone has shown.
What remains for hypnosis is modest and indirect. Relaxation can lower general tension, and someone going through the difficult course of ERP might use a calming practice to take the edge off a hard day. That is a comfort beside treatment, not a treatment, and it would be a mistake to let it stand in for the exposure work or to delay reaching a clinician trained in it.
Anyone whose days are eaten by intrusive thoughts and rituals deserves the approach with the strongest backing. For OCD, that means ERP and an evaluation by a mental health professional, with medication considered where appropriate. A relaxation technique can keep company with that path. It cannot do its job.