In ArcGIS Online, on the layer properties menu, the Remove choice should be in a different location on the menu, maybe within its own separators. As far as I know, you can’t undo this operation, which makes it kind of dangerous.
Being next to Rename on the menu makes it worse because renaming layers is so common. More than once I’ve changed symbology, changed pop-ups, and then removed a layer I meant to rename.
