I don't think you can remove lines like that, unless the window is a listbox-type. You may want to try putting reference numbers next to every line, then you could make a command that searches for a line beginning with whatever line reference number you enter, and deletes it. I think /filter would probably work well for this.
/filter -wwcpzx @window @window 832 *
(untested)
-genius_at_work