Hehe.. Ok, what happened there is when you clicked "back" before the user was deleted, you read in your users.list file with the user in it before the user was deleted.. then the "delete" finished and then the "back" process rewrote overtop of the modified users.list file with the OLD data.. so the user is in the file, but is actually gone. I'll create a function so that when the user is gone, but in the list (when you delete him again), he'll be removed from the file.
Workaround:
remove the user from the /usr/local/directadmin/data/users/reseller/users.list file.
*NOTE: once you click any button, DA *will* finish the process regarless of if you press stop, or back or not. Even with a closed pipe, the process will continue. (For example, when you create a Site Backup, you can in theory go elsewhere right after you start it and then it will complete on it's own while you browse somewhere else).
Yes, it's a type message that coders add when they think something will never happen .. but as we saw, that isn't always the case, but should be an easy fix.