According to OpenAI, they don't use data sent to the API for training and delete it after 30 days. So your concern is misplaced unless you think OpenAI is outright lying about their policies.
That's only for ChatGPT. The APIs are governed by [0]
> We will only use Customer Content as necessary to provide you with the Services, comply with applicable law, and enforce OpenAI Policies. We will not use Customer Content to develop or improve the Services.
That language seems to be doing a lot of heavy lifting. A more straightforward phrasing would've been "we will never process or otherwise consume customer content once it has been delivered to you". As written, they could use it to train GPT-5 or what-have-you and refuse to share it with you, making that exempt as it is apart from "services". Or all manner of other shenanigans, if they have competent lawyers.
You can't really read the language at face value. 'Services' is defined term in the contract:
> “Services” means any services for businesses and developers we make available for purchase or use, along with any of our associated software, tools, developer services, documentation, and websites, but excluding any Third Party Offering.
Of course it's still language, and one can quibble with any language, but it's reasonably restrictive.
That’s my point though, they can clearly use your data to train as long as they don’t sell/share those models themselves, as per this contract.
At the end of the day you can’t blindly trust your data is safe, even with a solid contract (bad actors exist, after all). So whatever you do, do it at your own risk.