Is it possible for Plesk installer to show warnings during component deletion if this component is used at the moment?
This feature is not implemented yet. Take part in our product improvement by referring the following link: Plesk UserVoice.
The top-ranked suggestions are likely to be included in the next versions of Plesk.
To avoid removing of components in use, check if the component is used before deletion. For example, if some PHP version is planned to be uninstalled:
1. Log into Plesk.
2. Open Tools & Settings > PHP Settings and check Domains column:
3. Click on the number of domains to see the list of domains that use this PHP version.
4. If the PHP version still should be uninstalled, switch PHP handler in Plesk > Domains > example.com > PHP settings.