To further this discussion, I'm ready to update my phone to 10.0.14936.1000, but I'm told that I can't because "we temporarily need 1.18 GB of space to download."
Under storage, I'm told that my phone has 6.11GB used out of 7.28GB.
That 6.11 GB is made up of 3.38GB system & reserved, and 2.31GB apps and games. I have removed every single app except for those that aren't uninstallable. I have 0GB in Documents, Pictures, Music, Videos, Maps, and Temporary Files.
In other words, the only thing still taking up room that I have any control over is "Mail & Messaging," which is at 412MB. I have changed every account to only download the last 3 days worth of mail (no idea how to manually purge anything older, if that's even possible), deleted all promotional text messages, and changed the settings to only download texts from the last month.
How in the world can I install this update? Is my system footprint correct at 3.38GB, or do I need to hard reset in order to free some of that up?