I want to delete the system storage

System storage is the essential system files that your iPhone could not function without and temporary files like backups, cached items, and logs.

Not knowing how much yours actually shows being used, some things you can do to make sure it’s having the minimum needed used are:

First, Restart your device.

Optimize settings following https://support.apple.com/en-us/HT201656#recommendations

Lastly is to backup then erase all content and Settings. https://support.apple.com/guide/iphone/erase-iphone-iph7a2a9399b/ios