I've filed a utility patent application, nearly 17 months ago. At that time also filed PCT application, then withdrew the PCT application.
Is it possible to file a request not to publish the USPTO utility patent application?
No, as per this page The non publication request, if filed, must be filed with the filing of the patent application. If the non publication request is not filed with the patent application, then the patent application will publish in due course. If you wish to maintain the secrecy of your patent application until it matures into a patent, the only other option is to abandon the first original patent application and refile provided that this is still an option. Another downside for abandoning and refiling is that intervening prior art could be cited against your patent application during examination.
