To assist in your design work, you can change layer states and create new Layers or Layer Combinations, even if the Layer Settings attribute has been reserved by someone else.
However, to save and share these changes to the project, or to delete layers, you must reserve Layer Settings.
However, elements on deleted layers are NOT deleted if they are owned by other users. Such elements will be identified as having “MISSING” layers. These elements will be displayed on all outputs; their visibility cannot be changed.
If you find that your elements are located on a deleted (“MISSING”) layer, you should either delete these elements or move them onto another layer.
To easily identify which of your elements are on “MISSING” layers, just hide all project layers: elements whose layers are missing (plus any elements on the ARCHICAD Layer) will be the only elements that are still displayed.