I don’t use the Project feature of the Audacity but whenever i edit and
save any audio file then close Audacity it asks me to save the project
this really nags me, so how can i disable this prompt ?
I don’t think you can. Audacity’s job is to create a Project, not a sound file. It sees every job without a Project as a failed job.
Koz
It’s designed that way to try to protect folks from accidentally losing their projects - and lots of 'em still do 
Like you I don’t use projects most of them time for my LP transcription work - I just click the “no” on that message 
BTW many other software products do exactly this - and without any over-ride preference too, just like Audacity.
WC
It would have been lot better if there was a option to disable this prompt.