Why my lost iphone is removed from my icloud?

The message that you received is a scam, which is trying to trick you into thinking that you can get the phone back by providing some "details".......like your Apple ID and Password.

All this will do is is allow the bad guys who have the phone to unlock the phone so they can sell it again, not to mention that this will open up your other devices for unauthorized use of your personal data.

The best thing that you can do right now? Delete the message and any others like it that may appear. The phone is gone.

Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

Unfortunately, by responding to that scam message, you have given criminals the “keys to the kingdom” of your Apple ID. Any content that you saved to iCloud is now in the hands of these criminals, who can use it to steal your identity. Change your Apple ID password IMMEDIATELY, follow these instructions→If your iPhone, iPad, or iPod touch is lost or stolen - Apple Support, and review the information the criminals have to see if you need to change credit or debit cards or other personal identifications. And watch all of your accounts for fraud. Also, do not approve any 2 factor authentication requests you receive unless you know they are in response to something that you initiated.

icloud.losts-alarts.us/vbi is NOT an Apple or iCloud URL. It’s even mispelled “alerts”, which should be a dead giveaway.

Apple NEVER, EVER sends you messages or emails with links in them, and NEVER, EVER gets involved in lost or stolen devices.

And what is a “proper Apple number”?

I will let Lawrence respond, but you will not like the answer. Unfortunately, you have been scammed. This message was NOT from Apple Support. Apple does NOT send messages like this.