After I activated the premium plugins, there were two boxes on the screen. One is titled “Delete Customizer Settings” and says “Warning: Deleting your Customizer settings can not be undone.
Consider using our Import/Export add-on to export your settings before deleting them.” Followed by a list of things to delete. There is another box that says Import/Export and “Export your settings set in the Customizer.
Export Default Customizer Settings” with a list of things to export.