erase an encrypted USB stick

Hello ,

I have a backup USB stick which is AES 128 encrypted (MAC os X formatted) and I lost the password.

I don't care about the dat as it is a backup and the original is saved in multiple drives.

The problem is that I cannot format / Partition / erase or do anything.

Can some one tel me how to blank that stick and reuse it?

Thanks in advance as after a few days of searching and trying with PC's Diskmaker and many other "tricks" I am a bit clueless.

Gilles