Just turn off the clock/date in the tray, and then you can resize the bar to the width of a single icon if you wish.
The minimum width is the size of one contiguous entry in the bar.
The clock is a system notification which you can just turn on or off.
To resize the bar, right click on it, uncheck "Lock The Taskbar", and you can then adjust the width, as you would a normal window.
On several systems I have noticed that some software and various themes lock the taskbar width. If that is so in your case you may need to try a different theme. Sorry, but I have no idea which work and which don't.
Bar dragged small; Bar dragged larger;