The Xperia Z5 Premium E6853 mobile phone hard reset can be done in three ways. The first is with a software program called Xperia Companion and the other is by using either the codes or the menu system to reset the mobile phone. The Xperia Z5 Premium E6853 does allow for a reset by code unlike the Sony SGP621CE Xperia Z3 Tablet also listed on this website.
Always ensure that you are certain that you do not need the settings such as the APN settings or you dont need the data then you can reset your phone without much issue. If you however wish to reuse the data then you can backup the data and settings first with the Xperia Companion software listed on this website which allows for a backup onto your computer before the factory reset.
Hard Reset will erase all of your data
All described operations you are doing at your own risk.
Hard Reset Sony Xperia Z5 Premium E6853 by Menu
Hard Reset Sony Xperia Z5 Premium E6853 by Code