Yes, you have to remove all unsold items from the store before you will be able to sell again.
I would suggest that you remove everything, including the paintings. Sometimes there are problems with the consignment store if you have allowed items to go unsold. I would suggest, after removing the items you take the sim home, sell the unsold produce to the grocery store and the paintings direct from your inventory. Allow 24 sim hours to elapse then save and exit your game. Close the game and reload.
Hopefully when you next try to consign items the store will accept them. Watch for the consignment store message when you close the consignment screen. It should say something like "Thanks for consigning your items. I will let you know if anyone buys them". If you get the other message "Customers are getting bored with your items," you probably won't ever be able to sell anything through the consignment store using that particular sim. In future, try to keep an eye on your consignment items and remove any which are down to two days to ensure that you don't get the negative message. Never reconsign items which you have removed.