It is common that researchers collecting data using surveys will need to include the option for the respondent to be able to Withdraw from a study and have the answers that they have already provided deleted. Qualtrics does not offer a simple solution to do this, but there are a couple of options to achieve this:
1. On every page (or at least most pages) of your survey, add a question that asks if the respondent wants to withdraw from the study. This will not automatically delete the answers already provided, but it is easy enough to filter your results to look for anyone who said yes to any of these questions and then delete their responses. This is a simple way to achieve this end.
2. If you are looking to have this done automatically, without the need to manually filter and delete, this is what you do. You set up the same type of question as above, but use Skip logic on the question to go to the end of the survey. You then go to Survey Flow and click on Add a New Element here (will be green text). Then click on Branch, then add a condition, at which point you make the condition that they indicated in the withdraw question that they want to withdraw and click OK. Then click End of Survey and then Customize. On the screen that pops up that says Customize End of Survey, click on Override Survey Options and check Do NOT record Survey Response and then OK, and then save the Survey Flow.