How to delete songs of iphone 4 on the newest software?

I've deleted them by swiping it on the phone and clicking on "delete" but when I plug it in to itunes, the songs I've delete still show, but they don't show on the phone!

I'm not an expert on I Phones but don't you have to Sync it somehow. If not just ignore me.

Thats a pretty simple question. On your computer you should have itunes. If you on there delete the song you don't want in your music folder. Then connect you phone with the computer with the cable given from apple. Then just sync and your job is done.