Want toSelf manage. - Property manager won't let me

[Koti Reddy]

My class A property (in 4Sranch) is being managed by one San Diego property management company for the last 2 years (6%)

New extension starts for tenant from July and I want to self manage.Currrent tenant don't like to deal with the property manager as he never attended any of the issues on time also confused him with wrong notices which are not meant for our unit. I decided to self manage and asked the property management that I don't want their service after their listing term (end of may). I really like my tenant and want to keep him.

Property manager says I need to pay him for the future extension if the same tenant want to renew as he came in during his lease listing period 1 year back. 

Landlord expert's please let me know if that is a common thing or he is just threatening me. I might have misinterpreted the leasing terms and not sure if It is ok topaste them here? I came to know from other friends using the same property manager that he didn't let them change property manager showing the same reason.

He takes the payment for the whole 1 year at the start of the lease(not monthly). He doesn't keep track of expenses on home(anyways I take care of them as he was not responding) and that was inconvenient when the tax time comes.

I still don't understand how people can even change the property manager with out terminating/not extending the current tenant lease.