The practice that can help you past your learned bad habits of trying to edit as you write is what Elbow calls free writing.
主干：The practice...is what...
定语从句that can...修饰主语The practice,从句中的介词短语 past your...habits作宾语you的补语，as you write引导的时间状语从句修饰trying to edite。what引导的表语从句中用了call+宾语+补语的结构，what是宾语，free writing是补语。
译文：这种可以帮助你克服在写作的同时就试图编辑的坏习惯的做法便是Elbow所称作的自由式写作。