how to cancel N400 application or biometric?

You do not have to go to the biometrics appointment if you are giving up the case. You can further write a letter to USCIS requesting cancellation of the application. If you filed online, you can upload a message. I note that having one DUI is not an automatic bar to naturalization. While deniable as impinging on good moral character, the entire circumstances may be taken into account by the officer. Due to the limitations of the Lawyers.com Forums, Alan Lee & Arthur Lee, Esqs.’ (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.