Return iMac I’ve used

The 14-day return only applies to purchases made directly from an Apple retail store or Apple's online store per this published policy.

See:

Returns & Refunds - Shopping Help - Apple

If you are outside the US, the policy may differ or not exist.

If you purchased from an Apple Authorized Reseller or other independent reseller, their return policies apply.

You can within 14 days of purchase.