I believe they are called " cashews " & they allow graphical access to KDE's plasma desktop menu's, I've never tried but yes i would suggest that it is possible to remove them but
1. why would you want to.
2. be warned the whole plasma desktop is difficult to reinstate once gone, weather by design or accident.
3. I believe they are linked to such things as system tray & kick off menu launcher so it's quite possible you will loose these in the process.
Under applications in the kick off menu select help to read more on plasma.
Desktop HP Pavilion a1040a
Intel P4: 515J processor: 2.93 Ghz: 1.5 Gb ram
2 x sata HDD
ATI Radeon X300 SE PCI-Ex
Sabayon-9 Gnome x86
Laptop HP Pavillion dv6-7031tx Netbook
Intel core i7 3610 2.3 Ghz
Nvidia GeForce GT 630m