I have lost the phone number I used to sing in as apple ID

I have lost the phone number I used to sing in as happy ID

See -> If you've forgotten your Apple ID email address or phone number

If you've forgotten your Apple ID email address or phone number – Apple Support (UK)

How can I change or remove apple ID

1.

See this Apple article: Change your Apple ID -> Change your Apple ID - Apple Support (SG)

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

2.

If you have removed / deleted it, it is no longer valid, it simply no longer exists and it no longer works.

To understand about a deleted Apple ID, see the Apple articles below:

How to delete your Apple ID account

How to delete your Apple ID account – Apple Support (UK)

Understand and control the personal information that you store with Apple

Understand and control the personal information that you store with Apple - Apple Support

Get more help and assistant from Apple directly, see Contact Apple for support and service -> Contact Apple for support and service – Apple Support (UK)