To do this, simply download your product database from Tools > Database Import/Export.
Once you downloaded and opened the file, you will see a column named "MarketplaceEnabled". This is field allowing the product on the marketplace.
You can see that some of the products have the "TRUE" value, so simply change all of these to "FALSE" instead.
Once done, save it then re-upload it. This will disable them from being available in the Ashop Marketplace.
