The way to clear System Data is to erase your computer, however, this will make it unusable. Please read the following information. It will be useful in understanding this issue.
The Other Category can not be altered, modified, move or deleted since it is part of the Mac’s operating system. Doing so would corrupt the OS and render the OS inoperative requiring a Wipe and Re-Installation.
The Other category is a potpourri of files which include:
• System temporary files
• macOS system folders
• Archives and disk images (.zip, .iso, etc. - often found in the Downloads folder)
• Personal user data
• Files from the user’s library (Application Support, iCloud files, screensavers, etc.)
• Cache files
• Fonts, plugins, extensions
• Other files that are not recognized by a Spotlight search
• Media files that cannot be classified by Spotlight as a media file because they are located inside of a package
They can be located anywhere on your hard drive. The files that you have control over are located in the Documents, Downloads, Pictures, Music and Movies folders.
If your HD is too full, this may be a good time to seriously consider adding an external drive for storage. Then you can move files onto it and then delete them from your HD to clear needed space. Easy to do and problem solved.