I am using Inquisit's web based function and my IRB wants assurance that "No information is collected or retained from study
participants, including IP addresses".

From browsing this forum, it seems like IP addresses are automatically saved. Is this true? If so, can this function be written out of the code?

No. I am not aware of any post here that would suggest that. No IP information will be logged to the data files, unless you deliberately decide to do so w/ the computer.ipaddress property.

Regards,

~Dave