Maybe open the console, click the rack (You have to be careful what you click, console is picky) and type disable and maybe the dagger will fall to the ground.
Save beforehand, of course.
thanks! that worked in getting rid of it.
just wish there was a way to get the one back that was stored

...
Every time I've disabled and item or person via the console, that item/person has disappeared from my game never to be seen again. unless that is the intention, I'd use a little caution there.
yep, this is what happened for me as well. which is odd because the console obviously "sees" Mehrunes Razor but for some reason can't add that specific one to your inventory via player.additem.