My journal is already bugged with two "Collect bounty from Skald" entries. This idea came to my when I opened details for dawnguard.esm in CK loading windows.
Fact 1: If you have a mod that adds a quest which you complete then you remove the mod, that quest disappears form journal even if completed(...at last for a particular mod I did that)
Fact 2: What I noticed in dawnguard.esm is that it has some entries marked with "D" meaning deleted(...and I thought it must mean it deletes something from skyrim.esm)
So, my idea was to brutally delete BQ01 to BQ04 and save as a mod. The user will need to start with this mod, save the game, then remove the mod.
Unfortunately it didn't work even it with the mod saved as esm (CK only method: rename, load, save). The entries were still in my journal and if I type in console "help BQ01" it still sees it with 00 prefix.
I just leave this here, maybe will serve as a starting point for someone that has more ideas.

PS: any idea if this works http://psx-scene.com/forums/f289/how-delete-skyrim-locked-quests-103687/ or something else involving editing save file? Steps 15, 16 there could not convince me if up till there the entries were not gone.

I have the same problem, not found any solution. The skald fix on the Nexus and the unofficial patch both work ONLY if you don't already have a broken journal entry. I'd really love to find a way to delete these from my journal.