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。