Do you know wich they offer?
AFAIK Coinbase only lets you withdraw money to your Bank account, if you want to sell your bitcoins and receive money to Skrill or Neteller then you'd have to use other exchanges like LocalBitcoins or sell here in the forum, but do remember that on LBC you wouldn't sell directly to the exchange, you will be selling to traders, the site just acts an escrow, so that you only release Bitcoins once you have received the money in your account. But I wouldn't recommend you trading with Skrill or Neteller due to the fact that a scammer may try to get charge-back after the deal is over, I don't know about Neteller but there have been instances where people have successfully charged-back Skrill.