How to make such disappeared nickname like that? There three ways to make your nickname blank or not shown. First, you can use a software to do that job. Just find that program on the web. Second, you can remove your nickname by change the language to yahoo main land or Chinese. Then figure out by yourself how to make your nickname disappear via yahoo mainland.
And finally, the easiest way to disappearing your nickname is fill your nickname via your yahoo profile editor page with “&” symbol (without quotes). Amazingly, your nickname will never be shown again in chat room (using official yahoo messenger, not unofficial yahoo messenger).
The weakness of this ways is, if some one who has also empty nickname that create using same method with you, yahoo messenger will detect an duplicate nickname arisen, then yahoo will shown your ID. It’s mean if someone make same empty nickname with you with same method, this method will not working.
To avoid this error, you have to add another “&” symbol to differ with others nickname (like “&&&&”).
You can also use “&” character to make spacing nickname with your nickname. That mean, before your nickname, you will see a blank or empty character. It will make your Id or nickname get higher position in list ID of yahoo messenger chat room.
You can also fix that problem by combine two methods of invisible nickname.

I found this method by my own knowledge, please make sure if you spread this method, don’t forget if you found from this Free Yahoo Tools Download blog
Happy Great Chat