How do I hide a quote in the customer portal?

You cannot hide a quote sent to your customer in the customer portal.

Every quote, except the ones that are in the Draft status, will be displayed in the Quotes module of the customer portal.

If it is necessary, you can try deleting the quote. This will remove the record from the customer portal. But keep in mind that deleting is permanent, and cannot be undone. However, before deleting the quote, you can create a copy of it using the clone option.