Amethyst Metadata File (.amf) ​

This file is stored in the Metadata Cache folder within %appdata%/amethyst and it's a JSON file containing the metadata of the given audio file, the filename is gonna be the same same as the name of the audio file it stores metadata for If the file is renamed amethyst will have to re-cache the metadata, meaning there may be copies of cached files.

eg. enjoii - Never Say Goodbye.flac => enjoii - Never Say Goodbye.flac.amf

Regeneration ​

These files are generated when Amethyst analyzes a file for metadata. They can be rewritten by forcefully refreshing metadata within Amethyst from the dropdown menu or with the shortcut CTRL + ALT + R.

Deletion ​

As mentioned above, all metadata caches are stored in %appdata%/amethyst/Metadata Cache. Simply deleting the files within the folder will achieve cache deletion.