I have all of the songs in my library in the lossless format(about 5300 songs/606 gigs). I am wantong to convert them to AAC 128 VBR. Every time I convert a song it leaves two songs, the lossless and the AAC. Is there a way to convert the songs and just leave the AAC version, or do I have to do through and manually delete all of the lossless versions?