For Windows 10.
Select the folder and do right click on the mouse. A context menu appear. Look at the Read-only check box in General Tab. If it is un-ticked, it is not read-only. Else it could be partial or total read-only. Go to Security Tab and look at the various permissions to find out.
If you have proper rights on the system, you can try un-checking the box in general tab and click apply.
Hope it will solve the issue of write permission.