How to delete unsupported tags in .m4a files?

Hi,

to delete unsupported tags in .mp3: Ctrl-X -> Ctrl-V is a great workaround.
But on my Mac I have 90% .m4a files.

And unfortunately this doesn't work for .m4a files. Unsupported tags remain in the file.
To be more precise, there is still information in the file, but via exiftool I don't see any tags or anything.
But the information is still in the file. Source for the information: NI Traktor Pro

Any ideas how I can delete such informations?