The best way to free up space in your storage is to complete orders on the board to get rid of some of the items you have.
 
It is also possible to sell items directly from your storage. To do this, open the storage, tap the item you want to sell, select the quantity using the + and - buttons, and then tap Sell.
Sell Items
You can also upgrade your storage to increase its capacity:
  1. Tap the barn icon in the bottom left corner of the screen.
  2. Tap Goods.
  3. Tap Upgrade on the left side of the screen.
Storage Upgrade
To upgrade the storage, you will need sets of tools. Here’s how you can get them:
  • Complete special shiny orders on the order board.
  • Open chests received for completing multiple orders in a row.
  • Unlock achievements.
  • Find bonuses while catching butterflies.