Hi, I had the layer problem in MEP and also when trying to clean up Arch dwgs sent to us,
Use the obscure ACAD command - "laydel" this will allow you to select layers to be deleted! CAUTION this gets rid or EVERYTHING on the layer also so be careful - this command will also allow you to delete the "defpoints" layer too!!!!! - here is another trick - if you lock a layer you want to keep it won't show up in the box of layers you can delete. Good Luck
Rick