One user is not able to unwatch a calendar to avoid geting all the notifications. They have also removed all checks against email notifications in theor profile with no change.
In place of the usual "Watch" "Stop Watching" options is just "Watching"
It sounds to me like the user is encountering this - https://jira.atlassian.com/browse/TEAMCAL-248. Can you verify if the user is watching a page that embeds the calendar? In order to stop "Watching" the calendar entirely, he will need to "Stop Watching" the page where it is embedded.