Google does not own or retain any data that is submitted through Google Translate. Google states that data ownership remains with the user in its Terms of Service policy:
Your Content in our Services
We believe that you own your data and preserving your access to such data is important. If we discontinue a Service, where reasonably possible, we will give you reasonable advance notice and a chance to get information out of that Service.
Some of our Services allow you to upload, submit, store, send or receive content. You retain ownership of any intellectual property rights that you hold in that content. In short, what belongs to you stays yours.
View Google’s Terms of Service policy here: https://policies.google.com/terms?hl=en