Hi, Frenchieo. I'm Robinson, and I’m happy to help you today.
Here are some options that you can try to delete the old account.
Option 1: Delete the account using Control Panel
1-Right-click on Start then click on Run
2-Type: Control Panel and click on Ok
3-Click on "User Accounts" then click on "User Accounts" again
4-Click on "Manage another account"
5-Click on the account that you want to delete and then click on "Delete the account"
Option 2: Delete the account using the user account settings
1-Right-click on Start then click on Run
2-Type: netplwiz and click on Ok
3-Select the account that you want to delete and click on the "Remove" button
Option 3: Delete using the Windows PowerShell
1-Right-click on Start then click on Windows PowerShell(Admin)
2-Type this command and press Enter:
net user [Microsoft account username] /delete
Note: Replace the [Microsoft account username] with Microsoft account that you want to delete
I hope this information helps. If you have any questions, please let me know and I'll be glad to assist you further.