Existing Tenant receives $200/month discount to "resident manage"

[Joel Harris]

I am purchasing a 4 plex with one of the tenants receiving a $200 discount on monthly rent in order to be a resident manager. I'm not sure what this includes, but I would be much more comfortable with a professional management company handling issues. 

Does anyone have experience divesting a tenant of "manager" powers? Are there any safe ways to go about it? Should I just be forthright and tell the renter that I will have a management company take care of the situation, and let him know to expect his next contract to be $200 higher?

Thanks!