If you meant to go back to previous feature update (2004, 1909, etc)you can do the below steps. Otherwise, follow the steps in the other 2 replies.
Go to this site and download the latest version of Rufus: https://rufus.ie
Run it, and under the window, you'll see a settings button. Click on it and set the Check for updates to Daily (default) (it might be chosen by default), then click Check now. When that's done, close the update window, and near the SELECT button in the main menu, there's a down-pointing arrow. Click on it and choose DOWNLOAD and click on the DOWNLOAD button again. Choose the options as per your preferences and device, then proceed to make a bootable disk (MAKE SURE A USB DRIVE OF MORE THAN 8GB IS PLUGGED IN BEFORE MAKING A BOOTABLE DISK. THIS WILL REMOVE ALL THE FILES IN THE DISK, TOO.).
Then, after making a bootable disk, boot your device from the USB (tutorials are available online), then follow the rest of the steps.