Sometimes I use the “Run command” functionality in KDE (Alt+F2) to start a program - that’s faster than clicking all the way through the menu until I found the entry and given the fact that the dialog is saving a history I usually only type one or two characters and have the full command line available. But the command history grows and grows - and sometimes I want to remove old and no longer used entries (like gaim which is pidgin now). That’s not possible ouch at least not in the “Run command” dialog or in the preferences. The Mozilla/Firefox-way (Shift+Del) also does not work.
Time to descend into the personal .kde directory and dig in some config files …
The file in question is: ~/.kde/share/config/kdesktoprc and if you open the file in your favorite editor you can see (among others) a section named MiniCli. Remove the no longer needed items from CompletionItems and History and save the file - but take care that KDE is not changing the file in the meantime. My own background changer (which set’s a new background every minute) is such a candicate - so KDE is updating this file and your saving would overwrite the file.
The changes take effect after the next login.