The unfortunate answer here is that all medical insurance claims require a ICD10 diagnosis to file. Even if you do not believe there is a diagnosis to utilize, one must be used to bill, and your professional obligation is to pick a diagnosis as accurately as possible.
Many providers do not want to share diagnosis information with insurance companies. Unfortunately you simply will not be able to file successfully to insurance with a diagnosis missing from your claim submission form.
Please include the most accurate diagnosis you possibly can when coding for mental health insurance claims.