Write an article based on this "Back up important data. Connect your external hard drive to your computer. Open File Explorer . Click This PC. Right-click your external hard drive. Click Format…. Select a file system. Click Start. Click Ok. Click Ok."
If there is data on the drive you need to keep, make sure to save it on another hard drive.  You can transfer files to your computer's internal hard drive, use a USB flash drive, or upload to a cloud storage service such as Google Drive, DropBox, OneDrive, or iCloud. Most external hard drives can be connected to your computer using a USB or firewire cable. In some cases, an external hard drive may need to be plugged in using an AC adapter. It has an icon that resembles a folder with a blue clip. You can usually find File Explorer in your taskbar at the bottom of the screen. If you don't see it, press ⊞ Win+E to open it. It's in the sidebar menu to the left.  This displays all external and internal hard drives connected to your computer. If you don't see "This PC", look for the name of your computer.  It's next to an icon that resembles a computer monitor. This displays a pop-up menu next to the hard drive.  If your external hard drive has a specific name, it will be listed in File Explorer.  Otherwise, it may be listed as "USB Drive" or the make and model of your hard drive. The amount of space each hard drive has is listed below the drive name in File Explorer.  Right-click the hard drive with the amount of space that matches your external hard drive. It's in the menu that appears when you right-click on your hard drive. Use the drop-down menu below "File System" to select the file system you want for your external hard drive.  There are three main file systems you can choose from.  They are as follows:   NTFS:  This file system well with Windows, but may not be writeable on Mac or other systems.  Select this option if you only plan on using your external drive on Windows computers.  exFAT:  This is usually the default file system.  It works well with all versions of Windows and recent versions of macOS.  It may require additional software on Linux, but is still supported by more devices than NTFS.  Select this option if you plan on storing large file sizes and plan on accessing your external drive on other devices, such as macOS.  FAT32:  This is an older file system that can only store files that are less than 4 GB. It is, however, compatible with more devices.  Select this option if you don't have any large files and need the largest compatibility across multiple devices. It's at the bottom of the Format menu.  This displays a pop-up warning. It's in the pop-up warning.  The pop-up warning informs you that all data on the external drive will be erased.  This acknowledges the warning and formats your drive.  It may take several minutes depending on your computer hardware and the size of your external hard drive. This appears in a window that pops up when the drive is finished formatting.