By design, Novi AMS does not allow admin users to delete invoices or other transactions. Instead, transactions must be deleted within QuickBooks. This ensures that an association's accounting team is the only group that can void or delete an invoice.
Void vs Delete
Deleting an invoice is final. It removes the transaction from your records as well as a member's Member Compass. Voiding an invoice leaves a record of the transaction while updating the amount due to zero. Neither action should be done without careful thought.
Deleting Transactions in QuickBooks
Note that as a QuickBooks user, your actions will be recorded in their audit log, accessible by your accountant and other full admin users in perpetuity.