Navigate your phone settings and first go to about phone. From there go to software information. You should see your build number. Tap the build number several times in a row and developer options will be unlocked. This gives you access to developer options and a whole new set of customization features
It is how it starts… You need it to allow USB connections and debugging so that you can utilize external tools to format partitions and overwrite them with your own ROM. Gotta ditch that bloat.