How do I remove launchers from the KDE panel?

At least on my KDE4 desktop I can remove a launcher like this:

1. right-click on the right-most side of the panel and select Unlock Widgets in the popup menu
2. right-click again on the right-most side of the panel and select Panel Settings now displayed in the popup-menu
3. move mouse on the desired launcher icon and click on the X in its popup to remove the launcher (you can also click and drag it elsewhere if you want to)
4. right-click on the right-most side of the panel and select Lock Widgets in the popup menu (to prevent accidental panel changes)

The accepted answer also works in KDE 5

(to ascertain the version of your KDE: `Start Menu (alias Application Launcher) > All Application Selector along the Bottom > System (Cogwheel Icon) > Info Centre (Icon of an extension card) > [Get a new Dialog] > About System on the left)

Inspired by Kde Plasma 5: How To Add And Remove A Widget From Panel In Kde:

Right-click on the panel or an icon in the panel. You will get the option to "UNLOCK WIDGETS"

Now a "Toolbox" Icon appears at desktop's bottom right (actually looks like a stylized Royale with Cheese or a stack of Oreos.)

Right-click on the toolbox icon and select "Panel Settings" (or just left-click on the toolbox icon directly). A puzzling configuration element appears (above the panel if said panel is on the bottom of the screen.)

Now move the mouse pointer to the icon you want to remove. A pop-up menu with a kill button appears. You can also right-click on the icon, then a pop-menu with the option "Remove this icon" appears.

Do the expected thing. You are then notified that the icon has been removed!

After that, lock the widgets again.

Phew.

(IMHO, this is what happens when overdesign takes hold. It would be better to have a separate management interface with a "time machine" to have rollback functionality somewhere in System Settings. Then the lock/unlock (mis)feature would be wholly unnecessary too (I vaguely remember this from KDE 3 maybe).)