Updating CRM Contact Info with Survey and Empty Field

Good afternoon,

I am working on a survey to allow my contacts to update their own information. Thanks to the integration of Zoho CRM and Zoho Survey, I could populate the answer with the existing information, and people can update them if needed.

However, I realised that if I delete an imported answer and let the field blank (for example, my contact want to remove his/her work address and doesn't wish to give a new work address), the CRM keeps the past answer. It means that even if my customer deletes an information because it has become irrelevant, this information remains in the CRM (except if I manually delete it, of course).

Is there something I am doing wrong here?

Thank you.