If you wish to terminate your tenancy after the lease agreement has expired, you must give 21 days notice in writing prior to vacating. If your tenancy agreement is still current and you wish to vacate, you are breaking your lease.
This means you are responsible for meeting rental payments until a suitable replacement tenant is found or until the expiration of the lease, whichever is sooner. You will also be responsible for advertising costs, the letting fee and GST. Contact your Property Manager immediately if you decide to terminate your tenancy and find out exactly what your obligations are.