strange device on my account QQ

Based on the information provided, it appears that the account in question is configured as a local administrator account on the device.

In Windows, local administrator accounts have full control over system resources and user management on that specific device.

If you need to remove, disable, or downgrade this account, the recommended approach is:

1. First create an alternative administrator account on the device. This is required because Windows does not allow administrative permissions to be modified unless you are signed in using another account with administrative privileges.
2. After signing in with the newly created administrator account, you can:

• Remove the existing account,
• Disable it, or
  • Change its account type from Administrator to Standard user using:
    • Settings → Accounts → Other users → Change account type

Standard user accounts are recommended for daily operations, as administrator accounts have unrestricted access to install software, modify system settings, and manage other users on the device.

Reference:

• Local accounts in Windows
• Manage user account types in Windows