Recently I put a bounty on this question at max bounty:
How can I remove items from the allowed values list of a select field that has data for the values?
There seems to be a consensus as to a general direction to take (use VBO) but no answer I was hoping for. I was going to let the community decide by voting up what it felt was the best answer, but after a decent amount of exposure, no one has voted on anything, so it doesn't seem the community believes in one over the another.
What would be protocol here? Do I just choose one? For the answers that suggest VBO, who would the credit go to, perhaps the person who answered first? Ultimately, however, the question really doesn't have an answer yet.