What is the steps for clearing used ashtrays from table?and why we do it in this way?

to put a clean one above or near  than remove the dirty ashtray we should never just empty it 

Or carry a service tray with two clean ashtray.

Put one top of each other.

When replacing on the table, with courtesy place the two ashtray  beside / near the dirty ashtray.

Cover the dirty ashtray with one clean ashtray on top. So cig. ashes will not spill on the table when removing it.

Remove the two ashtray from the table placing it on  your tray.

Arrange the clean ashtray on the table  in a way that it can reacheable.

Before the leaving the table,Ask for satisfaction or further assistance, just in case they might add something.

 first i must put a clean ashtray than  

i should remove the used one

because we must never clean it