Your landlord can only end your tenancy by following the correct process. Secure Housing Executive and housing association tenants can only be evicted if a court believes that they have broken the tenancy agreements. It's easier for a landlord to evict an introductory tenant, but the landlord still has to get a court order. Think carefully and get advice before you take any action to end your tenancy. It can be difficult to get a new social tenancy if you've given one up.
The Housing Executive or housing association can use different methods to get the money that you owe. If you're worried about the rent you owe, get help from a charity that provides money and debt advice.