You understand the business of landlording before you get started. You don't landlord for the purpose of evicting someone. You landlord for the purpose of exchanging keys for a duration for money, specifically by creating a leasehold estate that you sell to your tenant.
Your tenant has the leasehold, you dont have the money, in part because it sounds like you didn't collect any before you handed over the keys or confirm your tenants' ability and history of paying.
You now want to nullify the leasehold. In general this is the eviction you ask about.
You are now reliant on a court in your jurisdiction to enforce the contract law with respect to the lease language and prevailing local ordinances.
I cannot speak specifically to NY courts but they have a reputation as tenant friendly so you need to demonstrate your professional approach and locally required paperwork such as a certificate of occupancy, business license, etc. All lined up to make it easy for a judge to agree with you.
You have an uphill battle. Turning off utilities (as mentioned in another post of yours) is not a professional move and will bias many judges against you. No certificate of occupancy may mean your original lease contract created a leasehold contrary to a public policy of NY which could put a judge in a bind if they found your case compellingm
If a competent lawyer would cost $15k then it sounds like it might be cheapest to offer the tenant a couple thousand for the keys and a signed release to walk away-spend a couple hundred on the lawyer for this. Do not give them the money until they are out and give you the keys.