Hi Colin.
I don't remember how in version 3.
In version 4 there is a "startup" directory in which there are the files we need.
Create a folder with an arbitrary name and move unnecessary files to it.



I looked at the description, everything is simpler there. Find the files whose name starts with a two-digit number, these files control the buttons we need. For example, I don't want to use "Nodeeditor", which means I don't need this button, then we look in the directory for a file named "97 Nodeeditor.js" and change its name to "-97 Nodeeditor.js" which will disable the button. Here is another example, I often use "Nodeeditor" and I need the button in the addon that launches "Nodeeditor" to be the first from the left, then rename the file to this form "01 Nodeeditor.js", which will move the button to the leftmost position.