This usually happens because the school account was added to Windows as a work or school account, which can register the device in the organization directory and let the school enforce restrictions.
Try this first:
- Open Settings.
- Go to Accounts > Access work or school.
- Select the school account.
- Choose Disconnect.
- Confirm with Yes.
- Restart the laptop.
If the device was also managed through Intune, disconnecting it removes the device from management. After unenrollment, access to school resources can stop, Company Portal access is removed, and organization-enforced settings are no longer required.
If the school account is no longer listed there, but sign-in prompts still appear, remove saved sign-in credentials:
- Open Credential Manager.
- Check Windows Credentials.
- Remove entries related to Microsoft 365, Office, or Teams for the old school account.
If the device still appears connected and access to the laptop is limited, the connected device can also be disabled from the work or school account device page:
- Go to the My Account devices page.
- Review connected devices.
- Select Disable for the old device.
Important: disabling a device cannot be undone by the user. The organization administrator would need to add it again.
If the laptop is shown in Company Portal, it can also be removed there:
- Sign in to the Company Portal website with the work or school account.
- Go to Devices.
- Select the laptop.
- Choose Remove.
If the school blocks websites through software they manage, only the school IT department can remove or change those restrictions.
References:
- Add Your Work or School Account to a Windows Device
- Remove your Windows device from management
- Manage your work or school account connected devices from the Devices page
- Manage User Accounts in Windows
- Remove device on Intune Company Portal website
- How do I remove a microsoft account that I no longer have access to? - Microsoft Q&A
- How do I remove Lightspeed Filter Agent on my school laptop (Windows 11)? - Microsoft Q&A