Google Adsense Guide | How To Remove a site from your sites list

If you no longer want to use a site for site-related actions such as showing ads, you can remove it from your sites list. You can remove an individual site or multiple sites from your sites list.

Note: Be aware that removing a site stops all ads serving on the site.

Remove an individual site from your sites list

1. Sign in to your AdSense account.
2. Click Sites.
3. Click the Down arrow  next to the site you want to remove.
   Note: If the Remove button is greyed out, make sure your site doesn't contain any other subdomains first. After you've removed the subdomains, you can remove the site.
4. Click Remove.  Your site is removed.

   You can always add this site again later, but we'll need to check that it's ready to show ads again.

Remove multiple sites from your sites list

1. Sign in to your AdSense account.
2. Click Sites.
3. Click More   Remove sites.
4. Select the checkbox next to each site that you want to remove, then click Remove sites.
   Note: If the checkbox next to the site is greyed out, make sure that your site doesn't contain any other subdomains first. After you've removed the subdomains, you can remove the site.
5. Click Remove. Your sites are removed.

   You can always add these sites again later, but we'll need to check that they're ready to show ads again.

Source : https://support.google.com/adsense/answer/9130109?hl=en&ref_topic=9137703