returning to 8.2 from 9.0

[Fbsd8]

Rodolpho Henrique Orlovsky Eckhardt wrote:
> On 13:49 Sat 10 Sep     , Fbsd8 wrote:
>> After erasing the front of the HD nether 9.0 or 8.2 will install.
>> Can I use livecd dd command to erase the second copy of the GPT?
>> Where is it at?
> 
> Try "gpart destroy -F <disk>". You should be able to recreate a GPT or MBR scheme after that.
> 

gpart destroy -F da0
gives this message
gpart: geom 'da0': Invalid argument
da0 has the HD in question connected through usb port.