The appcmd help is a little vague and I can't seem to figure out the proper escape or quoting sequence.
appcmd set config -section:defaultDocument /-files.[value='main.html']
Remove a collection element with the specified keys in the
collection of the "system.webServer/defaultDocument" configuration section.
This works fine:
appcmd set config -section:system.webServer/rewrite/globalRules /-[name='rulename']
This does not:
appcmd set config -section:system.webServer/rewrite/globalRules /-[name='rule name']
The rule in question has multiple spaces and a forward slash (/) in the name.