In Moon Invoice, you cannot delete a product because it is already linked to existing invoices. This applies not only to invoices - if the product is linked with any other module, deletion will not be allowed. However, if you create a new product that isn’t associated with any invoice, you can delete it. Please note that once a product is deleted, it cannot be restored.

If you simply want to hide a product instead of deleting it, kindly refer to the link below for step-by-step guidance.

https://help.mooninvoice.com/hc/en-us/articles/18649761637273-How-can-i-archive-a-product-in-Moon-Invoice