Deleting Multiple Files At Once

Hello Community!
Firstly let me apologize if this has been brought up in the past, I performed a quick search of the forums and didn’t see exactly what I was looking for.
I have used Horizon for a long time now to add songs to my Rock Band 3 music collection (custom songs, not pirated), and it has always worked great! Thank you for that. Rock Band 3 has a track limit of 3000 songs, so I figured “No problemo! I’ll just fire up the ol’ Horizon and delete the songs I don’t play.” As I have discovered, I can only seem to select a single song at a time. After deleting a single file, the list refreshes and returns me to the top. I was using the Xbox 360 itself to delete songs one at a time, but that was a very time consuming process. Horizon allows me to inject multiple files at once, is there no option to delete multiple files at once?
My experience with Horizon is limited, so please be kind to me!
Thanks in advance for your assistance and suggestions!