You can create a very small survey and try those things (this is what I had to do for you as well now), if you do not want to do it with the main survey.
So if you would have gone past the first screen of activating the survey you would have seen this:
At this point you decide if you want open access or closed access mode (tokens).
If you will decide closed mode, you will be asked if you want to activate tokens.
If you want to leave the closed mode, you just delete the token table.
I think the process is quite straight forward. And I don't see how you activate closed mode without wanting it (only if you just click through the process without reading it).