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I had to reset my Amazon Echo the other day but couldn’t find a way through the menu on how to do it. In the Alexa app, you can Deregister an Echo from your account.
In order to reset your Echo to factory settings, you need to pick up your Echo and locate a small pinhole at the bottom with the label ‘RESET’.
Insert a pin until you feel it click. Hold it pressed for 5 seconds until the color ring turns blue. Set it down and wait for the color ring to turn orange. You can then perform setup again.