I have connected and used external display 1920x1080
After disconnecting the display it looks like panel remained huge size and I can not resize it as panel button is outside of the desktop:
You right click on the panel and select Unlock Widgets, then right click again and Panel Options → Panel Settings. Then you can select Maximize Panel option from More Settings or try to use some other options to manipulate the panel
>
> You right click on the panel and select Unlock Widgets, then right click
> again and Panel Options → Panel Settings. Then you can select
> Maximize Panel option from More Settings or try to use some other
> options to manipulate the panel
>
…and if none of these should work, you can always delete & re-create the
panel.