Is this an allegation of harassment?
Why do you want to have contact with this person?
Sorry for the delay.
I see your problem.
The difficulty with this is that it is not the PIN but the fact of the allegation that is recorded on DBS.
However, I can completely see why you would not want this on your record. The difficulty with PINs is that they have no status in law. They are entirely an invention of the police essentially to deflect allegations from prosecution.
However, you can ask them to remove it. It would probably be better to get a solicitor to write to them asking them to reconsider.
If they refuse then you could judicially review that decision although that is a very expensive action to take and one with a high test. You might well find somebody at the Bar Pro Bono Unit would offer representation for free as it is a point of public interest but you would stil have to bear court costs.
Can I clarify anything for you?