The only way to delete a Sales Order or Invoice is through the Salesforce Delete Lightning Action. This option is only available to system administrators and not common staff users.
Sales Order Lines may be deleted on a Sales Order record, but this does not delete the parent record. This is the case for both CPBase and Lightning Communities.
Portal users also cannot delete a Sales Order. Removing Items from the cart will not delete the Sales Order record generated in the backend. If the cookie expires for a Sales Order, the record will be regarded as an abandoned order. A new Sales Order will get created for the user’s next purchase.
Likewise, Sales Orders cannot be deleted from the backend Payment Page or Rapid Order Entry (ROE). The record itself can be modified, but it cannot be deleted.