You just need an ordinary motion passed at the next AGM or at a EGM before that stating that the Strata wish to terminate the current SM with xx days notice (check what notice is required in their contract).
A simple majority of those voting is required (or if different lot entitlements a majority of entitlements).
It might pay to get a replacement SM lined up with another motion to employ company xx on termination date of current SM.
The only problem would be if the current SM has a long fixed term contract with penalties if early termination so check their contract