Second guessing myself now but I remember finding such a setting (in addition to the reverse... Unmonitoring if deleted from disk), and thought it sounded dangerous.. but it was disabled by default from memory.
One other thing is that Radarr has a recycle bin... I think 7 days retention by default. I've never checked it myself but maybe you can get your stuff back from there?
Of course if it's empty then I guess Radarr didn't delete them.
What a stupidly titled article and post combination