Just go to settings> Storage> select delete SD memory. and wait a few minutes then your memory will be empty immediately.
What is System Storage on iPhone? System storage is the space where your iPhone stores two kinds of data: core and temporary system files. In case you didn't guess, core system files are necessary for your iPhone to function. These are the files behind the iOS operating system and built-in applications.
If you use Safari, you'd find Safari under Settings, select it and tap “Clear History and Website Data.” Another easy tip is to simply delete all those apps that you don't use anymore, thus freeing up more system storage. You just need to press and hold the app you want to delete.
You just have to:
All computers have system storage – a crucial component that stores data on a long-term basis. This component ensures that the data you use (apps, audio and visual files, text files, etc.) can be accessed when you turn the computer on next time.
First, the system storage on the iPhone contains things like items that your phone could not run without, but may also contain temporary files like backups, caches and certain logs. To find how much space your System storage is taking: Tap on Settings.
Select the Storage tab and press Manage. In the window that appears, you can see some of the useful suggestions. "Store in iCloud" lets you transfer all your data to cloud storage and reclaim some GBs on your Mac. The second option allows you to delete the heaviest files, like movies and programs.
We recommend following these steps in the same order.
“System” can be wildly different sizes, sometimes it's 7 GB or so, but it can also easily be 10GB, 15GB, or even a whopping 25 GB or larger too, often even on the same device type.
“System” in iPhone storage consists of essential system files that your iPhone could not function without and temporary files like backups, cached items, and logs. You can see how much space System is taking up on your iPhone by going to Settings -> General -> iPhone Storage. Scroll all the way down to find System.
Reasons your iPhone's System Storage Gets Cluttered First, the system storage on the iPhone contains things like items that your phone could not run without, but may also contain temporary files like backups, caches and certain logs.
Open Settings > Safari and choose Clear History and Website Data. If you have a lot of Safari tabs open on your iPhone, you might want to close most of them, too. Clearing your Safari data might reduce the size of Other. You might also want to change Messages to save fewer old messages.
You can go through your iPhone trying to delete every little cache that could grow the size of Other storage, but if you really want to make it as small as possible, you need to back up your phone and reset it. This can take a little while. The best way to do this is to use iTunes on your Mac or PC.
Checking Current “System” Storage Size in iOS
How to check your Mac storage via "About This Mac"