I tried it, but it's still there :-( All the files with the name of the resource were removed from my disk, yet after saving the project, I still get a new, empty resource (wxPanel in my case).
Note that the resource actually has a different name than the filename of the .wxs file. The resource is called pnlReview, while the filename is pnlReview1.wxs. I think that was caused by a crash shortly after creating the resource the first time. When I recreated it after the crash, the name was changed to pnlReview1.wxs.
Anyway, I boldly edited the project file with an XML editor, removed the reference to the wxPanel that offended me, and it all seems fine now. I also filed a feature request.