Hi cactusjoe and welcome to our forum!
The answer of your question is here:
Welcome to Live Support my name is Sophie how may I be of assistance?
You: Hi there
Sophie: Hello there! How are you today ?
You: I would like to ask you about the Winward's policy reagrding no deposit bonuses, ok?
You: Let's say I get a 20 no deposit bonus, I play and finally manage to win and my balance at the end is 100. How much I would be able to withdraw?
Sophie: Please note that the free $20 sign up bonus are used as for the enjoyment of players and have no value of themselves. Furthermore winnings from the sign up bonus can be played only and cannot be withdrawn and/or exchanged for any prize.
You: what about the ASKGAMBLER code?
Sophie: No sign up bonus can be withdrawn,
You: so the aforementioned terms apply, right?
Sophie: Yes, the condition I told you above.
You: Thanks Sophie and have a nice day!
So, I'm afraid you won't be able to cashout anything from the no deposit bonus but only to explore the games in real mode and have some fun eventually!