You can click on the challenge to get the option (at the bottom) to change to another challenge.
But the challenge is something that you gradually get credit towards as you ride (e.g. workouts, free rides, group rides, races). It’s not something that you have to do in one session.
Thanks Steve - good to know. I noticed that my other challenge was the Everest challenge. I’m fine with either challenge, but what if I don’t want to participate in a challenge? Seems once you make the choice/commitment (I suppose), there’s no backing out.
You should leave it on the Everest challenge, that is how you get the Tron concept bike. Why would you not want to participate?
Reason for reluctance to participate? Great question to which I’ll provide tongue in cheek answer - fear of commitment 
Seriously though, no reason. Simply unfamiliar with this new “game” and figuring out how all the pieces in the puzzle fit together.
Tron you say? I think you’ve just answered my (unasked) question about the neon wheels I see on occasion. Everest it shall be then!
Just to be clear on this, while you have selected the Everest ‘challenge’, there is nothing specific that you need to do to. You will simply do the rides you want to do and Zwift will track the cumulative elevation you gain on your rides. Eventually (hopefully) you will have climbed enough vertical over the course of your rides to conquer the Everest challenge (and earn the Specialized Tarmac Pro bike), and then you can continue on this challenge until you earn the ‘Tron’ (Zwift Z1 Concept) bike. So, its a sort of passive challenge. (Not to say, of course, that knowing it’s out there won’t motivate you to climb Alpe du Zwift 15 times in one day; I’m just saying that you don’t have to view it as a challenge if you don’t want to.)
Everest Challenge (First time up) earns the Trek Emonda…at least for me.
Thank you Nigel - understood. I enjoyed my first exploratory rides last night. There are numerous great features to the software that will continue to bring me back. There are some features offered by other training software that seem to be absent, but my mental jury is still out as to whether this is a good or bad thing.
don’t double click OR click when zwift’s countdown is near the bottom.
Often I have clicked just as the self-countdown has ended and been taken straight into he last world I used.
Very annoying on an iPad or iPhone where your not sure if the screen press registered.
I have the same problem
What is the Issue @paul_murphy1
Did you read all the possible solutions above.
Yes i just found out about the intro ride and am getting ready to ride it now
yeap its the intro ride.
thank you !
Suggest that they add this to the knowledge database on Zwift support as I just spent 30 minutes with the support team trying to figure out why I couldn’t pick a world and a tutorial for first ride was never mentioned.