You've also misunderstood the ClearWorld Parameters:
ClearWorld [entities][,brushes][,textures]
Parameters
entities (optional) - True to clear all entities, False not to. Defaults to true.
brushes (optional) - True to clear all brushes, False not to. Defaults to true.
textures (optional) - True to clear all textures, False not to. Defaults to true.
ClearWorld [entities][,brushes][,textures]
Parameters
entities (optional) - True to clear all entities, False not to. Defaults to true.
brushes (optional) - True to clear all brushes, False not to. Defaults to true.
textures (optional) - True to clear all textures, False not to. Defaults to true.