Update: I did a programming!
Okay, so I plagiarized a thing a smarter person made by changing a file name wrote a script that will close your Exalt client with the press of a button (or two, in this particular case).
First, download and install AutoHotKey.
Second, paste the following into a text file (note that the second line sets the closing buttons to ctrl+esc; change as you see fit) (also, this works for non-Steam, not sure if Steam users will need a different file name–I really have no idea what I’m doing):
;Force close Realm
^esc::
Run, taskkill "/f" "/im" "RotMG Exalt.exe"
Return
Third, save the text file as <whateveryouwant>.ahk and put it in a convenient location because you will have to re-run the file every time you start your computer.
Fourth, test it beforehand to make sure it works.
Fifth, use this when your Exalt window needs to die, fast.
Explanation: this will close your Exalt window even if there is a pop-up, or if you otherwise are having trouble closing it. This is a variation of the previously linked Oh Shiet Button, but this version works with Exalt. Hope it helps!