Content of main domain example.com is removed when additional domain example2.com is removed only if the conditions below are met:
- Subscription example.com was created in Plesk.
- Additional domain example2.com was created inside this subscription with
httpdocsas Document root directory: Subscriptions > example.com > Add domain
- Wordpress was installed on example.com: Subscriptions > example.com > WordPress > Install
- Document root directory for additional domain example2.com was changed from
httpdocsto new one
example2: Domains > example2.com > Hosting Settings > Document root
- Additional domain example2.com was removed: Domains > example2.com > Remove
This is a Plesk bug with ID PPPM-8911 which is planned to be fixed in future Plesk updates.
As a workaround before additional domain(example2.com) removing go to Subscriptions > example.com > WordPress > Scan.