My husband recently got the 200gb plan. I have the 50gb We are now family sharing on his 200gb but I am still getting charged for the 50gb. How do I cancel that plan from mine without losing what I have stored

Did your husband share the 200GB plan using the instructions in the "Share iCloud+ with everyone in your family" section of Share iCloud+ with your family - Apple Support ?

Did you ten use the instructions in the "Switch from your personal iCloud+ plan to your family plan" section of that same support article?

If both of the above were done, the following should be the result:

If a family member is already paying for their own iCloud+ plan, they can choose to switch to your plan or keep their own and still remain part of the family. When they switch to the shared family plan, they get a refund for the remainder of their personal plan. They can't keep their current plan and use the shared family plan at the same time.

I that didn't happen, contact Apple Support. See: Contact - Official Apple Support