To withdraw Nectar you will need to have a whitelisted Ethereum address. Through whitelisting your address, it will be added to an approved list of addressed which have permission to send and receive Nectar on the Ethereum blockchain.
If your address is whitelisted, proceed with the withdrawal as you would with any other ERC20 token.
If your address is not whitelisted, visit the Nectar withdrawal page here to whitelist your Ethereum address.
Whitelisting your Ethereum address will allow you to send and receive NEC tokens to/from other whitelisted addresses.