bitbake-layers remove-layer should also accept just the layer directory if there's a matching layer present in bblayers.conf rather than expecting a valid path. (This would be consistent with us showing this same directory name when bitbake prints the list of layers when running a build).
Fix merged to master: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=22e8c6cbd3070d65741a1fd7f05a40373c236a50