not sure what you mean by 'object', if you mean a multi level structure with many attributes, a trick is to have another empty variable, and use that to asign your actual variable when you want it empty.

Or if you want this even cleaner , make a function exporting the same structure empty, that way in your actual code, there is no need for extra local variables called 'empty structure XXX'

Yes @Dorine Boudry , you're right and that's what i exactly meant, and i understand your suggestion, even in this case devs need to create as many as functions to deal with the number of structures that we create.

yes, agree it would be nice to have a built in function that works for all structures

another alternative, 

with no extra actions, and no local variables, 

but with an extra node in your flow :

Use deserialize of an empty object into your structure, then assign your variable to the result of the deserialize