I don't think there is a way to remove ONLY one sub (in this case Auto_Open)
But there IS a way to remove a macro  Module.
Now, if you make sure that all of the subs in a given Module can be deleted
(or move all subs except Auto_Open to another Module)
then you can remove the single module.

Now, why do you want to remove it?
Wouldn't it be simpler to have it test for certain conditions and only run
if the conditions are met?
(Like, only run if the file  is called "ThisFile.xls" and is located in
"D:\ThisPath" ??)