The only way to start completely fresh with an empty Collection and the like is to use a new ID. While you can delete your characters, your Collections data and the like will remain intact and your save data is tied to your platform ID. So, if you wish to start fresh, you'll have to use a different ID that hasn't played the game. Clearing the save data in its entirety is not a service that Bungie offers. You can start fresh by either using a different ID on your platform normally or through Cross-Saving a brand new platform ID from a different platform. So, if you normally play on Steam, you can either use a new Steam ID, or you can set up Cross-Save with a new XBL ID, PSN ID, or Stadia ID that doesn't have any save data and make sure to select it as your active save data (not Steam).