Hi Jane,
Unfortunately, it is not possible to directly switch a business profile from our Full Accounting range (such as the Large plan you currently have) to a Basic Accounting plan like Sole Trader. These two products use different navigation and features, so a downgrade between them is not supported.
In this case, you must close the incorrect business by hovering over the Building Icon (top right) > Settings > Close business. Once completed, you can add the correct Sole Trader business by hovering over your business name (top right) > Add New Business > Select the Sole Trader type. You will need to re-enter the entries in this correct business type.
Tommy