Non-informative error during the WordPress plugin deletion:
PLESK_ERROR: Could not remove plugin "Plugin Name" version 2.3.1 because it has been installed on instance ID (12)
It is unclear how to get the domain name using the ID.
It is a Plesk bug with ID EXTWPTOOLK-3573: WP Toolkit errors show instance ID instead of an instance name. It will be fixed in the next Plesk versions.
Until the fix becomes available, use the following workaround to find out the instance names using their IDs:
Connect to the server via SSH;
Execute the following command:
# plesk ext wp-toolkit -info -instance-id 12