To delete an invoice, go to Options > Delete. To be able to delete an invoice, the role must belong to a permission group with level 3 - Delete in parameter Invoice product - process supplier invoices.

If using preliminary recording, the invoice will be deleted from the ERP system when the integration program runs. If you do not user preliminary recoding, the invoice will be deleted only in Palette. 

The invoice will be deleted on the specified accounting date in Palette. Thereafter, the functionality in the integration with your ERP system will determine how it is done there. 

It is only possible to delete invoices with status Active

In Palette, you will be able to see deleted invoices in Reports > show Invoice.