Legal Question in Landlord & Tenant Law in California

It depends. If the property management company is also the owner and there is a new owner, then maybe, depending on the terms of the transaction between the buyer and seller. Most likely the assets, including payments owed, were sold with the property, but not always. If the company is just a managing agent, then of course they can enforce them. The fees are owed to the landlord. That doesn't change just because the owner changes agents.