My iPhone is saying there is an update iOS 12.1.4 waiting to be installed later tonight. I put the phone on charge every night but it just does not update. This morning's message says there is not enough room for the update and to manage storage in settings. I have been into settings and discovered 15.5GB of 16GB Used. I have deleted unused apps and taken off some photos but about 75% of used storage is "Other". What is this and how do I get rid of it? Anybody know please?