Also I'm having trouble locating /response/core/actions/header-actions.php is it in the editor? I can't seem to find it.
You won't be able to use the built in editor on the file because it's located in a sub-directory of the theme. You will have to use your ftp client or file manager to access the file for editing.
So do i need to just delete the hyphen everywhere it occurs between line 91 and 146?
The file is well commented, so once you see it, you will be able to tell what titles, and on what pages, will be affected if you change anything. Don't forget to explore the settings in your SEO plugin. There may be some title settings you can change there as well.
Some reference material for the title function: Function Reference/wp title