Hello,
To disable the NAT rule:
set security nat <nat-type> rule-set <name> rule <name> disable.
To re-enable it:
delete security nat <nat-type> rule-set <name> rule <name> disable.
To delete it:
delete security nat <nat-type> rule-set <name> rule <name>
<nat-type> is source, destination or static.
Regards,
Rushi