After "unsubscribing" (mods are installed by "subscribing") from a Steam Workshop item there are a dozen respective files all around the game installation location and the mod is still active in the game. Is unsubscribing supposed to delete the mod files or do I have to manage local Workshop content manually?
According to this (and my own experience removing mods), the files are not actually removed. They still exist in the games folder. You have to go in and manually remove them yourself.
For example, they would be still located here:
File Location: C:\Program Files (x86)\Steam\steamapps\common\Counter-Strike Global Offensive\csgo\maps
Also here: C:\Program Files (x86)\Steam\steamapps\common\Counter-Strike Global Offensive\csgo\maps\workshop
Unsubscribing will stop updates from occurring.