Dynamically create the same instances of the class (this is mandatory) ... to remove or change the properties of all ever created instances of the class NewLay - I don't know how to properly write the syntax. Maybe a prototype like that?
If you're talking about js objects, you will need somewhere to keep links to them. If no reference objects will live not long, they are the garbage collector will remove. But if he remove them is to change nothing.
If you want to change HTML elements with class it_is_new_lay, something like this:
$('.it_is_new_lay').each(function(){ let elem = $(this) elem.html( 'hello' + elem.html() ) })
lay = new NewLay(); lay = new NewLay(); lay = new NewLay();
every time you completely overwrite the contents of the variable, and you have there will remain only the most recent value.