If you want to clean your storage without deleting your files, you can do it by deleting cache of apps.
Cache is temporary and useless file generated by apps.
It is 100% safe to delete those files. It will not delete anything from your app.
And, Some apps like YouTube, Facebook, Instagram, Chrome generate over 500 MB of cache. If you delete it, it will clear much storage of phone, without affecting any data.
To delete cache of apps:
1. Open settings
2. Click on Apps
3. Select the app (like Facebook)
4. Click on Storage
5. Click on Clear Cache
Done!
I recommend you to delete Cache of YouTube, Facebook, Instagram and Chrome every week.
