Layers Will Not Delete

[nmtltd]

How do I get rid of layers in a drawing that do not delete when I hit the delete button on the layer manager dialog?

Solution:
Layers that can not be deleted by the delete button on the layer manager dialog can have any of several possible things to look at. Most likely it is because the layer is referenced by something in the drawing.  One possibility is that the layer is defined within a block. When the block was defined, the person that defined the block included an entity in the block definition that is inserted on a specific layer. That applies to attributes within the block. The only way to get rid of the offending layer is to explode or
to redefine the block. To check for this problem insert each suspected block on a blank drawing, explode the block, then try deleting the layer if it appears in the drawing.

Another way is by using the 'Purge' command.