You can avoid old inventory cluttering up your account by marking Items as expired when they're broken, lost, or sold.
Expiring a single Item
Click Items, next click an Item
In the header, click Actions, then click Expire
Or click Unexpire item (if it's currently expired)
Expiring multiple Items in bulk
Click Items, then make sure you're in the Table view
Use the checkboxes to indicate the items to move
Click Bulk actions, then click Expire items
When an Item is expired, it no longer counts towards your account quota
Once an Item has been used in a Kit, Reservation or Check-out, it's no longer possible to delete it completely.