Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
Did you have a Microsoft 365 business plan? The sign in here typically is for business account, so that it can sync OneDrive files from business account to your File Explorer, because your personal account already by default syncs as built in.
If so, this is how you can remove this account. Can you go to your Windows Settings > Accounts > Access Work or School (note, it is the briefcase icon, not the litt person icon). Then see if the business email address is still listed? If so, click on it and then disconnect it.