Creating a credit note with incorrect details or by mistake means you can't delete it. You can edit it or mark it as void, which removes its values but keeps it for reference.
You can delete credit notes that are still in draft because they don't show up on your ledgers. Whether you edit or void the credit note depends on if you've already allocated it to an invoice or refunded it.
NOTE: You need full access to the Sales option to void or edit saved credit notes. With restricted access, you can only edit or delete draft credit notes.
If you’ve refunded the credit note, you need to reallocate the refund before you can edit or void it.
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NOTE: Sage 50 allocates a credit note to an invoice, creating a customer transaction. Remove this transaction before you can edit.
Unallocating one invoice and credit note doesn't affect the remaining transactions. If the credit note covers multiple invoices, edit the amount to pay and save it. For example, if the invoice is $50 and the credit note is $100, the amount to pay will be -$50.