CAD tip # 3589:

In older AutoCAD versions (or in AutoCAD 2004/2005) you can perform the following VBA macro to erase (remove) the layer filters (use e.g. the VBASTMT command, all on a single line):

For Each ent In ThisDrawing.Layers.GetExtensionDictionary("ACAD_LAYERFILTERS"): ent.Delete: Next ent

In AutoCAD 2005, add also (single line):

For Each ent In ThisDrawing.Layers.GetExtensionDictionary("ACLYDICTIONARY"): ent.Delete: Next ent

There is also the "REMLAY" VLISP downloadable from the CAD Studio (ARKANCE) VIP server. Or you can use the DeleteFilters.VLX utility available on Download (APPLOAD the VLX file).

In AutoCAD 2006 and higher you can also use FILTERS command.