EDIT: TL;DR How do I remove a panel from a screen I can't see?

I use an external monitor with my laptop, which I occasionally disconnect. On this monitor I have configured a panel with some widgets. After the last time I disconnected the screen, Plasma is treating it as a different screen. It does not load the panel or the background, but when I open the Add widgets side menu, the widgets that are added to the respective panel appear to still be loaded. This wouldn't be such a problem if I hadn't added the Global menu widget, since now apps don't show their menu bars.
How do I remove the screen completely from Plasma's memory, or at least remove the panel?

Also, here's my xrandr dump:

Code: Select all

Screen 0: minimum 8 x 8, current 3840 x 1080, maximum 32767 x 32767
eDP1 connected primary 1920x1080+0+0 (normal left inverted right x axis y axis) 290mm x 160mm
   1920x1080     60.03*+  48.03 
DP1 connected 1920x1080+1920+0 (normal left inverted right x axis y axis) 160mm x 90mm
   1920x1080     60.00*+  50.00    59.94 
   1920x1080i    60.00    50.00    59.94 
   1600x1200     60.00 
   1680x1050     59.88 
   1280x1024     75.02    60.02 
   1440x900      74.98    59.90 
   1280x960      60.00 
   1280x800      59.91 
   1152x864      75.00 
   1280x720      60.00    50.00    59.94 
   1024x768      75.03    70.07    60.00 
   832x624       74.55 
   800x600       72.19    75.00    60.32    56.25 
   720x576       50.00 
   720x480       60.00    59.94 
   640x480       75.00    72.81    66.67    60.00    59.94 
   720x400       70.08 
DP2 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)


I believe it's DP2, that's the problem. Assistance would be greatly appreciated.

I found the solution:

Open file ~/.config/plasma-org.kde.plasma.desktop-appletsrc

Find a text block containing 'appmenu', it should start with [Containments]. Delete the whole block.

Thanks for the invaluable help, KDE community.