I was wondering if I could delete the Premiere project once I export it into Encore using dynamic link or import it as an asset .
I will not be making any changes to the Premiere project.
No, dynamic link opens an instance of Premiere (I think that is the pproheadless.exe whatever), and is accessing the project.
If you export a file from Premiere, then you don't need the PR project. But there are so many times when you find that last change, I make no deletions until the final deliverables are done. (Of course, even then I don't delete!)