i lost my SIM card number

[Zeref~]

can help me to delete my old number
to replace a new number?

[Terminus]

From the Steam Support Article - Steam Guard Mobile Authenticator

Help, I lost (or sold) my phone and can't log in! What do I do?

If possible, you should contact your wireless service provider and get a replacement phone with the same phone number. Steam will be able to send SMS messages to your replacement phone, and you will be able to recover your account as described below.

If you no longer have access to your phone and don't have your recovery code, you'll need the assistance of Steam Support. Use the "Contact Steam Support" button at the top right of this page to get help removing your authenticator. If you don’t have access to the email address that is currently associated with your Steam Account please provide proof of account ownership within your ticket.

How do I remove the phone number from my account?

Log into the store in a browser, then:

• Go to your Account details (viewable under your account name, near the top of the web page).
  
• Click on Manage your phone.
  
• Click on Remove phone.
  
• You can remove the phone by typing in the current code from your Authenticator, or by sending your phone an SMS code. Choose one of these options and follow the instructions.

I'm getting a new phone soon. What do I need to do?

If you have two factor authentication enabled on your old phone, you should:

• Disable the authenticator (go to the Steam Guard menu and choose a different Steam Guard method)
  
• Log out of your account (go to the Log Out menu on iOS, or go to Settings / Log Out on the Android app).

Before you sell or give your phone away, we recommend doing a factory reset on it and removing personal information.

Additional Guide:

https://steamcommunity.com/sharedfiles/filedetails/?id=495405494

[Zeref~]

ok ty for help u.
iam done, just report in support steam,
email. id. no telp
and automatic admin reset your ID :3
ty admin