The default is to assume that the NIM machine names are the same as the xCAT node names. If you had used the "-n" option when you created the NIM machine definitions with the mkdsklsnode command then the NIM machine names would be a combination of the xCAT node name and the osimage name used to initialize the NIM machine. To remove these definitions you must provide the name of the osimage that was used.
Use the force option to stop and remove running nodes. This handles the situation where a NIM machine definition indicates that a node is still running even though it is not.
3) Remove the NIM definitions for all xCAT nodes in the group "aixnodes". Remove the NIM definitions even if the NIM node state is set to "currently running".