Police retention of DNA and fingerprint samples as part of the DNA and Fingerprint Retention Project (DNAFRP) is covered by the
Criminal Justice and Police Act 2001 (which removed the requirement under PACE to destroy samples where there was an acquittal or a court case was discontinued) and the
Criminal Justice Act 2003 (providing police with additional power to take these samples without consent from all persons detained at a police station having been arrested for a recordable offence).
Removal of records retained by DNAFRP and/or on the Police National Computer (PNC) will only occur if you can prove that yours is an exceptional case.
View the relevant ACPO guidelines here...
http://www.acpo.police.uk/asp/policies/Data/Re tention%20of%20Records.pdf