Cleaning out email records

We are in the process of cleaning our database and want to know if there is any way to just delete emails from contact records that have been sent to contacts from Infusionsoft (from marketing campaigns) and just leave the records of emails synchronised from GMail

No. You have no control over the email retention history in Infusionsoft.

Thanks for the answer Jeff - not what we wanted to hear, but good to get a response!