I sugges you chek the related registry keys. Before you modify them, please remember to back up the registry for restoration in case problems occur.
Exit OneDrive by right clicking on the OneDrive icon > Click Exit or Quit OneDrive. Open the Registry Editor by searching regedit > OK.
Navigate to HKEY_CURRENT_USER > Software > Microsoft > OneDrive > Accounts > BusinessX.
"X" is the amount of Business accounts that you have logged into previously. Find the specific one by looking at the UserEmail value. After you find the correct one, delete the entire folder (BusinessX).
Navigate to HKEY_CLASSES_ROOT > CLSID. Inside the folder, search (CTRL + F) to find keyword: OneDrive.
Find next until you find the one (string subfoler like ) that has the "OneDrive – xxx" (The name which is related to the school account) as the Default value.
Then delete this string subfoler.