You can make survey results anonymous, using "Conditions" feature.
Only "Single-choice survey question" and "Multiple choice survey question"types of questions can be done anonymously.
Step 1: Open the “Respondents & Requests” section of your report and add respondents.
Step 2: Choose a question, which you want to make anonymous (make sure that the question type is rather a "Single choice survey question" or "Multi choice survey question).
Step 3: Click on “Conditions”
Step 4: Choose "Make survey anonymous" option