Thank you for reaching out to us.
It is not necessary to remove dry skin for mikveh, as it is a natural part of the body and trying to remove it inevitably leads to more skin peeling off. You should just wash your feet thoroughly in a bath or shower, as you do other parts of the body.
We are sorry to hear of the distress that this has caused you. In general, OCD can present challenges for niddah observance. We encourage you to read our article and brochure on the topic, and to be back in touch with any further questions.