How to terminate a RE agent agreement

[Pier C.]

Hello. The contract with my current RE agent contains the following sentence: "Although Buyer may at any time withdraw from the fiduciary relationship existing between Buyer and Firm, the contract created by this Agreement may not be terminated by Buyer or Firm prior to its Expiration Date without legally sufficient cause." What is legally sufficient cause? I'd like to exit my current agreement and work with someone else, but that sentence gives me pause about how to proceed. I'd appreciate any insights.