How do I remove those numbers from Kubuntu's task manager?
I want to remove those numbers from panel whenever I open same app multiple times.
2 Answers
Short answer: I afraid you can't remove only <2> or <3> from appearing. There has to be a way to distinguish windows.
There is a workaround which I like and that is to use an alternate task manager which is available by default on a normal Kubuntu 18.04 system.
First, I see what you see with the default task manager with three Google Chrome windows:
With the default task manager, there is a way to collapse the three separate entries into one. See the answer by cipricus for more detail:
I prefer the alternate task manager widget* known as the Icons-only Task Manager:
*Note: to access the available widgets, click on the ☰ icon usually located at the right-end or bottom of your panel.
I also prefer a vertical panel and the images below are with a vertical panel:
Icons-only Task Manager with one Google Chrome window
Icons-only Task Manager with three Google Chrome windows
Notice the little green circle with a white plus-sign next to the Google Chrome icon. That indicates the presence of more than one window open for a particular program. The three entries to the right of the Google Chrome icon are there because I single left-clicked on the icon. I can then select the window I want to maximize (or whatever). Otherwise, those entries are not visible.
3(As a complement to the @DKBose's answer; as there is no way and no point in removing the numbers, I am just commenting on the setting to group the task manager windows of the same program).
The right-click More actions > Allow this program to be grouped setting means that the grouping will be allowed in case the task manager is full, because the default setting is to group only then. To always group, right click, Configure Task Manager (Task Manager Settings) > General and un-check "Only group when taskbar is full".
