You can safely delete the Microsoft Account (MSA) without affecting your Bell email account.
However, if you have any MS services connected to the MSA, those services could be interrupted if you delete the MSA. For example, Windows 8-10 user accounts, Windows parental controls, Office 365 subscriptions, OneDrive storage, Skype logins, and more all make use of your MSA.
I would recommend keeping your MSA active until you have a chance to make absolutely certain that nothing critical relies on it. At that point, if you still wish to delete the MSA, you should do so.