Can I Change Property Management Agencies mid Tenancy?

If you are unsatisfied with your property manager, yes you can change even if there is a current tenancy in place. The 2 contracts are separate from each other - the management agreement between the owner and the agency, and the tenancy agreement.

Check  your management agreement with the agency to see what length the notice period is and give notice in writing. Simple as that. Make sure you sign the new agreement and send it off.