Welcome to AC! Like Tall Guy said above, we can not determine what you should or should not delete.
Are you getting this info by setting>system>storage? If so, simply click on miscellaneous files. It should pop up a list of what's being considered miscellaneous files.
Or
Either by using a file manager app or by connecting your device to a PC.
Delete any folders that has names of previously installed apps that you do not use anymore.
Delete any temp saved files.