U can give them 90 days notice if u intend to occupy the residence I think perhaps contact the REIV if u r in VIc, it all depends on the terms of their lease so u may be able to get them out sooner than 90days depending on their lease
In Vic even if you intend to occupy the property you have to honour the lease. The lease runs with the property, not the landlord, and the rules are set up largely to protect tenants (if they weren't then people could find themselves homeless on the whim of their landlord). Check with your local real estate institute, or Consumer Affairs equivalent. In Victoria even if the tenants are "month-to-month" there are still rules about how much notice you must give (and it's usually longer than a month). You can give notice before the end of the lease, but cannot require the tenants to have moved out before the expiry of the lease. You should investigate the notice required, end date of the lease and consider your settlement period. If the lease expires in 4 months and you negotiate a 120 day settlement, you can ask the current owners to give the tenants notice, which will get the ball rolling sooner and have your tenants out around settlement. You are not entitled to do this yourself until after settlement. However some vendors will resist as once they have given notice the tenants may move out sooner, leaving them without rental income up to settlement.