How do you know this ?

Are you receiving the email/s to notify you a new account has been opened ?

"How can I close it"

You won't be able to close it yourself as you'll need the password to log in.

There's no 'forget password' link only a 'reset password' and you'll need to know the original  before being able to change it and log in.

Using the following link, click on Contact Us at the bottom of the page.

Then you'll see the automated assistant at the right side of the page.

Ask to speak to an agent.

You'll need to be very clear and have all your identifying  information ready to give the agent..

https://www.ebay.com.au/help/account/changing-account-settings/closing-account?id=4199&st=3&pos=2&qu...