Cannot remove "Approve Invoices" feature from a resource
If you receive an error that you cannot remove the "Approve Invoices" feature because the resource is an invoice approver or delegated invoice approver, check whether the resource is the engagement manager for an engagement.
By default, engagement managers can approve all invoices for their engagements. After you replace the engagement manager, you will be able to remove the "Approve Invoices" feature from the resource.