So.. yea.. i'm a total RockBand junkie. I have been playing Rock Band since the PS3 and the first game. I have since then bought every disc game minus the Lego one's out there and even got Blitz but that was just for it's awesome song list.
Nonetheless, the jump to current generation consoles (PS4/Xbox One) made me jump with joy. Finally, I could put away the PS3 and move it to the bedroom. It's now been several months since launch for Rock Band 4 and I plan to recap how to manage your library if you are like me and TONS of DLC with the exports being available.
I'm just going to get to it. The best thing to do if you want to make a very clean library with mainly songs you want vs the whole export setlist is to:
Backup your saved data to the PSN or XBOX Live services. This is in the Settings and Data Management areas. Just upload your current saves to the cloud if you have them.
Delete your Rock Band 4 app.
Then re-download it, once you do this on the PS4 it will then ask you to choose DLC to re-download with and in turn you can be selective and only choose those songs you really like or you can choose all.
There ya go! That was easy eh? :)