I used to have very specific views on this. After some contemplation a few things changed for me.
One of them was, it's just a bit of wood and cardboard with letters and numbers on it. The board in itself i don't think is too dangerous.
I think it's the ignorance of the user that could make it a less pleasant apparatus.
That being said i've used one a couple of times with a group of people, a more modern version made of cardboard. The difference between our group and some randoms was we had an experienced psychic medium taking the group. The other was we did extensive prayers, invocations, visualisations and set up a reasonable protective boundary which seemed to have worked fine. We got a great connection and some interesting answers.
I can understand wanting to get rid of it in a fashion that will make it harmless to others. Like i said, the board in itself isn't dangerous ( more often then not - there are exclusions) but the user can make it an unpleasant experience.
Wsteins got the right idea. I would suspect he's looked into magick. I would ritually burn the board and break the pointer and burn that too.