When you create a Whimsical account, we give you 4 free boards to use. The boards count toward your quota no matter where they are – even if you move them to the Trash.
If you moved your boards to the Trash, you can still restore them and then reuse them. To do this, go the Trash, select the board by clicking the checkbox in the top right (1), then click Restore from the menu above (2).
If after trying this you're still having an issue with the boards limit, feel free to send us a message.