http://www.zabbix.com/documentation/2.0/manual/appendix/api/host/massremove
I tried to delete macros from host by name, but it impossible because:
api/classes/CHost.php line 2149
if (isset($data['macros'])) {
$result = API::UserMacro()->delete(zbx_toArray($data['macros']));
if (!$result)

{ self::exception(); }

}
But API::UserMacro()->delete() must receive macrosid, not name of macros.