It's not his mental illness that is a problem. The CAUSE of the issue is immaterial - it's the noise and harassment issues that are lease violation. Do exactly what you do if this were any tenant - regardless of Section 8 - and that's issue a Notice To Quit for Reason Other Than Non-Payment of Rent. Send a copy to the Section 8 case manager. Refuse to be baited into any conversation on mental illness. Your only concern is the behavior which is disrupted to other tenants/neighbors and not in keeping with the legal mandate that tenants have the right to the peaceful use of the property. Should it occur again during the notice period, call the police so you have a record of the disturbances. Be sure you document the past ones with details, dates, time - no diagnosis.
With that Notice, the tenant will be given time to Quit/stop and correct before eviction starts. You won't need an attorney (unless you in any way reference mental illness). You'll want to be factually pushy with the case manager on the removal of the tenant and follow your state's court filing procedure for eviction if it comes to that (forms to fill out, a fee).
Again, focus on the behavior, serve the notice, be factually pushy with the case manager - and be done with this chaos. Always entertaining, huh?!!