1) You can sell your shares for $0 to Delisted.com.au. I spoke to them earlier in the week and they confirmed they are buying them and ATO would accept a zero dollar valuation. However, if BIG does ever recover then your shares are gone. Also you have to sell all of your shares as they won't split your holding.
2) You can sell or donate some shares to a 3rd party via an off market transfer. That's what I'm planning on doing.
BIG Price at posting:
$2.22 Sentiment: Hold Disclosure: Held