How could I remove/delete the rules from “FTP Authorization Rules” in Powershell?

I am trying to use Powershell to delete the "FTP Authorization Rules" from IIS7.

Thought I found the "add-webconfiguration" Cmdlet and can add a new rule in "FTP Authorization Rules" successfully,

but can't find any way to delete the rules.

In the get-help add-webconfiguration, there is a reference to remove-webconfiguration,but this cmdlet does not exist. If I try "get-help Remove-WebConfiguration", system will show 4 item as following but NO "Remove-WebConfiguration":

Remove-WebConfigurationBackup

Remove-WebConfigurationLocation

Remove-WebConfigurationLock

Remove-WebConfigurationProperty

And I also find the command "Clear-WebConfiguration",

but after reference and searching and trying, I still can't delete rules success....

Dose anyone know how to remove the specified rule in "FTP Authorization Rules"?

Or if "Clear-WebConfiguration" is working, please help to give a sample for "remove FTP Authorization Rules".

Thank you so much!!