After reboot, Rufus should have clean access to the device.
For persistent cases, the registry filter cleanup (Solution 6) or a temporary downgrade to Rufus 3.22 is your best bet. Windows 7 is an unsupported operating system as of January 2020, and its driver stack is increasingly incompatible with modern peripheral tools. However, with the fixes outlined above, you can continue using Rufus effectively for legacy bootable media creation. rufus access to device denied windows 7