It might be better to follow the 5.5.1 instructions in this case (the "without re-installing" option), that way it properly goes to a stand-alone config, ready to re-add to a new cluster (which you of course won't do).
Also make sure you have (working) backups and/or leave a clone of the/all VM's on node 2/3 so you have those still, till it is time to remove/re-install them.