Data deletion requests (ASD/C Diagnosis)

I am trying to understand if a diagnosis provided by Psychiatry UK can be taken off from my records under the DPA 2018. Additionally, since Pschiatry UK shares this data with the NHS, can I request for such deletion through a Data subject deletion request?

The reasons for such a deletion are not due to disagreement or an amendment required to the diagnosis - but that I am no longer a resident in the UK and may face immigration issues due to the existence of such a diagnosis in other jurisdictions.