Hi,
Below are some ways to gain a maximum RAM space on your galaxy note 4.
1. Delete text messages thread regularly as these take up a decent amount of memory specially when they are contained with multimedia like photos and videos.
2. Most apps contain cache files and may take a lot of space. It would be much easier to install an app like App Cache Cleaner and use it regularly.
3. Uninstall any apps that you never or hardly use. Preset apps can be remove if you rooted the phone however, the process may be risky and might cause damage. It would be better to disable these apps by going to Settings/Apps/All, selecting the app, and tapping Disable.
4. Move media files to external storage and set external storage as default storage. You...