Downgrade from creative cloud plan to Photography plan (20GB)

Try this.

https://helpx.adobe.com/manage-account/using/change-plan.html

Cancel what you have and buy new

To not pay an early cancel fee you need to talk to chat support

Be sure to remain signed in with your Adobe ID before accessing the link below
-you must also allow 'cookies' in your web browser for this to work
https://helpx.adobe.com/contact/support.html
-click the chat icon at the bottom right of the page to open a chat session
-the chat icon looks like '3 dots inside a circle' at the lower right
-type AGENT into the chat window to connect directly to a person rather than the AI