Every listing page offers a reporting route. You do not need an account for it.

In the form you provide: the exact address of the reported content, a category (unlawful product, trademark or copyright infringement, fraud, product safety, or other), your reasons, and a way to contact you for follow-up questions.

You immediately receive an acknowledgement with a case number in the form NA-YEAR-NUMBER. After the review you receive a notice of the decision including its reasons. If you disagree with it, you can file a complaint against the decision within six months.