Carefully follow this guide. When you’re done, you may want to implement some (if not all) of the recommended security measures and start backing up your site.
Hi Thank you for your answer. I already taken steps for making it safe. My curiosity about email that belong to wordpress.com.
Is it any official registration or haker did it!
Are you working with support from WordPress.com, Jetpack, WooCommerce, or any other Automattic product on your site?
Also, what is the first part of the email address?
No, I don’t think so.
This is the first of email “wadminw”
Yeah, that wouldn’t be a valid email address.
WordPress.com is not an email provider, so they only have internal-use emails under names like support, sales, billing, etc.
WordPress sites don’t require email verification though, so anyone could register an account with a fake email address.
Check Settings > General in your site’s Dashboard and make sure that the default user role for new registrations is not Administrator.
If it’s not, then the only ways a new Administrator would suddenly appear is if you created them, another Administrator created them, you were hacked, or your site is infected with malware.