On the taskbar I have a battery monitor icon that I can't get rid of.
It was there as a default when I installed (PC-BSD) - via unlocking widgets I couldn't manage so far.

you might need to:
1) delete that panel and start fresh
2) with plasma not running edit the relevant rc file ~/.kde[4]/share/config/plasma-desktop/appletsrc
-- quit plasma (kquitapp plasma-desktop)
-- backup the file
-- open the file for editing
-- there should be 2 adjacent "[Containments]" sections in the file with lines "plugin=battery" (or such)
-- remove the sections, save and then restart plasma (plasma-desktop)

google01103 wrote:you might need to:...

Thanks for the explanation, but luckily I didn't have to do all that; unlocking widgets once gain, this time I noticed that the battery icon DID have an X to delete it - how I overlooked that before beats me I'm glad it's solved so easily though.