If you look at the sensor in configure / groups, you can edit or delete parameters. Select the dasshed box on the rigt side and it will show all parameters for that object. You could also delete the value in the parameter from the modules.xml file, but you could get yourself in trouble if you break that xml file!
Thanks, I knew this method. In my case I'd like to delete from program code. Because, I'd like rewrite the PingMeAtHome extended program, that use Sensor widget instead of Status widget. So, the sensor name is the person name, which can set by program parameter. So the name like "bkenobi"
, the parameter is Status.bkenobi. But I change the name parameter to KaZe, the old parameter Parameter.bkenobi won't delete. So each parameter of change just to accrue parameters.