Laptop manufacturers are slowly dropping optical drives but you can USB external ones.
Better still, you could buy a flash drive (memory stick) of at least 8GB and download the ISO of Windows from Microsoft's site. Then use a utility named Rufus to make the stick drive bootable and incorpoarate the installation of Windows 10.
You would need to make sure the BIOS will allow USB Legacy Support so there is power to the ports before an operating system cuts in. Then, when you've swapped the hard disks over and are ready to go, restart the machine and tap Function 12 or whichever key you need to choose a boot option. Change it to USB or External drive just that once