Disconnect Jetpack Sites
Below is a step-by-step guide that will help you remove a self-hosted WordPress site you had previously connected to your WordPress.com account thanks to the Jetpack plugin.
2. In the site picker, find the site you’d like to disconnect. Click on it.
3. In the sidebar on the left, find the “Settings” menu.
4. At the bottom of the new page, find the “Disconnect Site” link.
5. Confirm the disconnection:
The site is now removed from your WordPress.com account and will no longer appear under your My Sites page.