You can now download CM12 mod for the Samsung Galaxy Note 4. CM a k a Cyanogen Mod gives users vanilla android experience that free of Samsung bloatware and other unnecessary applications that come pre installed on the Note 4. While a lot of work has been done in porting CM12 to Galaxy Note 4, it is still pretty much a work in progress.
You can download the build from here and try it for yourself. Keep in mind that currently a lot of things are broken and it is clearly not good enough for daily usage. For instance camera, telephony, data, audio and many other things are not working.
So if your Samsung Galaxy Note 4 is your main phone, stick to the stock firmware.