It might sound OP, but don't freak out! Yesterday, I killed a momentus for someone on smp1, but died in the process. Luckily I had my voter armor, however, I spawned at a bed from FNM. I was really mad, because I had to walk all the way back to spawn. Here is my idea: there should be a command like /set spawnpoint only at the waste/frontier portals. This would allow the player to reset their spawnpoint, thus spawning at the portals. I think it would prevent random bed spawning.
If it's a shared bed do this: Pick up the bed Place it a few blocks away Set your spawn Put the bed back in the original location That will clear your spawn while leaving it for others.
I tried that many times, never worked for me. I just sleep in another bed and destroy it. Also I found that the double bed works best. Top bed to delete spawn and bottom to set spawn.
Yes, I like bunk beds, and went into detail on this similar thread... http://empireminecraft.com/threads/suggestion-bed-spawn-removal-command.49370/page-2#post-890346
Weird. Definitely works for me. I do this 3-4 times a day. When it doesn't work for me it's usually one of two things...1) I forgot to click the bed before moving it back, 2) I placed the new spot overlapping with the old. Nice! I like that.