My son removed my Hotmail email address and added his address as the alias for my outlook account how do I change it back

To regain access to your original Hotmail email address and remove your son's email address as an alias, you will need to follow these steps:

1. Sign in to your Microsoft account: Go to the Microsoft account sign-in page and log in using your credentials.
2. Access the account settings: Navigate to the account settings where you can manage your email aliases.
3. Manage email aliases: Look for the option to manage your email aliases. This may be under a section like "Your info" or "Account security".
4. Remove the incorrect alias: Find your son's email address listed as an alias and remove it.
5. Add your Hotmail address back: If your Hotmail email address is not listed as an alias, you may need to add it back. Ensure that you enter it correctly and select the appropriate domain.
6. Set your Hotmail address as primary: If you can add your Hotmail address back, make sure to set it as your primary email address if that option is available.

If you encounter any issues during this process, such as error messages or restrictions, you may need to contact Microsoft support for further assistance. They can help you recover your email address and resolve any account-related issues.

References:

• Change a user name and email address
• Remove an email alias from a user

I apologize for the problem you are having, unfortunately if you remove an alias "@hotmail.com, @live.com, @outlook.com or @msn.com" you will not be able to recover or create a new account using it, you can check in the last section of the article below;

https://support.microsoft.com/office/add-or-remove-an-email-alias-in-outlook-com-459b1989-356d-40fa-a689-8f285b13f1f2