How can I *completely* wipe an MP3's metadata?

To strip id3 tags from an mp3 file you can use the tool id3convert. It has a switch called "strip", -s or --strip.

-s --strip Strip the tags instead of rendering (default=off)

Example

NOTE: Includes both id3v1 & id3v2 tags

before

$ id3info a.mp3 

*** Tag information for a.mp3
=== TIT2 (Title/songname/content description): Feist - I Feel It All
=== COMM (Comments): (ID3v1 Comment)[XXX]: Music video by Feist performin
*** mp3 info
MPEG2/layer III
Bitrate: 8KBps
Frequency: 22KHz

strip

$ id3convert -s a.mp3 
Converting a.mp3: attempting v1 and v2, stripped v1

after

$ id3info a.mp3 

*** Tag information for a.mp3
*** mp3 info
MPEG2/layer III
Bitrate: 8KBps
Frequency: 22KHz

References

• Erase and rewrite MP3 ID3 tags

Another tool that has the advantage of existing in Ubuntu repositories is eyeD3. Here is the command:

eyeD3 --remove-all music.mp3

mp3info only edits the ID3v1 tags, you need to use a program like eyeD3 or id3v2 that supports ID3v2

More comfortable is to use MusicBrainz Picard to tag your MP3 files (uses the mutagen library underneath).

Since mp3info only supports ID3v1, it cannot delete/wipe the ID3v2 info embedded in the MP3 streams.