To allow the presenter to choose to allow or not to allow the audience to clear response
The option not to allow clear response
We can do this right now! You may disable the Change Answer feature for any poll question you like. To do so: Click on the title of your poll question > go to Response Settings on the right side of the Poll Question > and then select Disable Change Answer.
You can see more details for how here: https://polleverywhere.uservoice.com/knowledgebase/articles/815070