You delete configuration statements, or complete configuration nodes by using the delete command.
Delete a configuration node.
vyatta@vyatta# delete interfaces dataplane dp0p1p1 address 192.0.2.21/24  vyatta@vyatta#
Now use the show command to see the deletion.
vyatta@vyatta# show interfaces dataplane dp0p1p1 -address 192.0.2.21/24 hw-id 00:13:46:e6:f6:87  vyatta@vyatta#
Notice the minus sign (-) in front of the deleted statement. This - shows that this statement has been deleted from the configuration, but the change is not yet committed. The change does not take effect until configuration is committed by using the commit command.
Another option is to use the compare command to see the change.
vyatta@vyatta# compare [edit interfaces dataplane dp0p1p1] -address 192.0.2.21/24 vyatta@vyatta#
Some configuration nodes and statements are mandatory; these nodes and statements cannot be deleted. Some configuration statements are mandatory but have default values; if you delete one of these statements, the default value is restored.