@SuperDragonite - appears that the purge was running whilst the server was crippled because a request came in at 09:31:52 to get the metadata for the movie and that was request was still in progress 2 hours later when the server crashed with OOM. This request is what led to the OOM failure.
In parallel to this the library was being scanned and the extras were being purged - but very little memory free
And it appears the purging has not been committed to the database and the new database copy shows them still there.
So for this approach to work, the metadata for the movie must not get loaded for any Plex client (eg Plex Web or if you have 3rd party products scanning the library) and the purging needs to run to its completion
It is looking like we have to resort to the brute force method worked out by @Volts and @shayanzadeh and @jakehoms and used by others here and in other forum thread
Which is to manipulate the database - to remove the extras for this movie and then after that update a number of tables removing orphaned items as a result of purging and then optimizing the database
The offending item in your case is metadata_item_id 15484
