EDIT: I hereby withdraw this product idea, as I have finally been able to clean up the layers in our manikin library myself. I describe the procedure in full detail here (there's quite a bit to it, as there are a few of the built in layers that you need to keep to maintain expected functionality).
I'm not entirely sure why I wasn't able to do this before, but it's likely one of two reasons:
PTC quietly changed the read only status of these types of models in the latest version of Creo
The system I was using at the time ignored the revised versions of the models I saved (*.prt.2 & *.asm.2), and instead continued to open the original versions (*.prt & *.asm) making it seem that the saves were ineffective.
Probably the latter; sometimes I'm just an idiot.
New Product idea would be for PTC to incorporate some of my layering fixes out-of-the-box. In particular, making sure that all the coordinate systems that are on the MANIKIN_DRAG layer are not also on any other layers, and providing unique layers for the line of sight, and center of gravity.
Original text of Product Idea as submitted in 2013:
Our site uses a small layering convention that works well for us. However, if you have a manikin loaded into your assembly, using layers becomes very difficult. The manikins have 40 layers, many of which start with numerals like our standard ones, so ours become interspersed with the manikin's. Since the manikin models are read only, these layers cannot be removed or renamed.
Adding to the frustration is that it is far from clear what these 40 layers are intended for. Some of them are empty (MECHANISM, MECH_PLANES, MESH, SKETCHES), so why are they there at all? Others seem redundant, such as the 5 for datum planes (01_ALL_DTM_PLN, 01__ASM_ALL_DTM_PLN, 01__ASM_DEF_DTM_PLN, 01__PRT_ALL_DTM_PLN, 01__PRT_DEF_DTM_PLN), where it seems one would suffice. Others are just confusing, and documentation on their purpose is not readily available (MANIKIN_DRAG, MANIKIN_FUNC, MANIKIN_REACH, MANIKIN_SITE).
I can envision a few ways this mess could be cleaned up:
Option 1: PTC cleans it up for everyone with a new manikin library. There will be a limited number of layers (e.g. for csys, planes, axes, points, surfaces, and one or two others for helpful manikin features), all of which would have MANIKIN at the start of their names, so they will all be grouped together in the layer list of a large assy.
Option 2: allow site managers to override the read only status of manikins, so they are empowered to clean up this mess themselves
Option 3: add a toggle switch somewhere in the layers dialog box, with 3 settings: "show all layers", "show manikin layers only", and "exclude manikin layers".