Why is my WhatsApp storage full of order photos and how do I clear it?

Open Settings, Storage and data, Manage storage, sort by Largest and delete in bulk. Deleting is permanent and removes the item for you only, so back up first if you need a record.

• Android: More, Settings, Storage and data, Manage storage. iPhone: your profile picture, then Storage and data, Manage storage.
• Sort media by Newest, Oldest or Largest, select several items and delete. Choose Delete any copies to remove duplicates.
• Deleting an item this way is permanent. Other people in the chat still see it.
• WhatsApp recommends a backup before deleting content on iPhone.