how do i delete old email address that is full of malware

If the goal is to stop using the old account in Outlook, remove it from the app:

1. In classic Outlook for Windows, select File.
2. Select Account Settings > Account Settings.
3. Select the old account, then select Remove.
4. Confirm Yes.

Important: this removes the account from Outlook only. It does not deactivate or delete the email account itself. It also deletes the offline cached content for that account stored on that computer.

If the account is a Microsoft account and the old address is still attached as a sign-in alias, manage it here:

1. Open Your info at Edit account info.
2. Select Remove next to the old address, or Add email if a replacement address still needs to be added.

If the old address is being used as a verification or backup method, remove it from Security info only after another method is already added and verified:

1. Sign in to My Account.
2. Open Security info.
3. Select Delete next to the Email method.
4. Confirm Yes.

Important: if the account may be compromised, first run a full malware scan on the PC, then change or reset the password, and review account settings such as connected accounts, forwarding, and automatic replies.

References:

• Remove or delete an email account from classic Outlook for Windows
• Change the email address for your Microsoft account
• Set up an email address as your verification method
• How to recover a hacked or compromised Microsoft account