You can see INBOX rules every mailbox:

GET:
$get-InboxRule -mailbox foo.user

You will get something like:
Name                          Enabled                       Priority                      RuleIdentity
----                          -------                       --------                      ------------
foo.bar.rule                  True                          1                             6404806255763783681

Of course, you can see the details by:
$get-InboxRule -mailbox foo.user |fl

REMOVE:
remove-InboxRule -mailbox FOO.USER 6404806255763783681