remove "encoded with" tag

After I encode a song in m4a format using iTunes, it comes with a tag.
Eg. "Encoded with: iTunes". (or other itunes version)
How do i remove this "Encoded with" tag?

P.S - The song is in .m4a format not .mp3

Can you see that field in the extended tags dialogue (press Alt-T)?
If so: can you delete it there?
If so: done.

i tried but it cannot be done from there, because "encoded by" is not showing up

do you mean "encoded by" or encoded with"?
Have a look at the help and the mapping and you will see that the field "encoded by" is available.
Not available is the field "encoded with" which refers to the codec (like lame 3.99) and cannot be removed.

it is encoded with but the file is m4a

i have same problem, what i find untill now this is write in <Encoded_Application>
if somebody knows any application wich can remove this tag let me know
thank you !