legal right to ban prior owner from property

[Marysue Connelly]

I purchased a 22 unit apartment building summer of 2018.  The past owner did self management and was lax and inconsistent with any type of policy.  He has been visiting the property and seems to be advising tenants on how to deal with new management. It seems he had a  tenant who had previously gotten favored treatment. She dislikes the current property manager due to lack of preferential treatment and enforcement of policies and procedures, as well as personality I assume. The management company overseeing the property enforces leases and property rules in a fair consistent manor.  We are concerned about the past owner encouraging legal issues and generally stirring up conflict.  Soliciting ideas on how best to handle this situation. Can we legally ban the past owner from the property?  Is this even a good idea since there is not 24hr onsite management to enforce this.  Also the conversation could continue by phone.  This property is C class with vacant units.  We are trying to gradually convert to better quality tenants.