How can toolbar button keys be deleted (to get rid of redundancy). The following explanation in the help file is unhelpful.
"You can only delete items in the Hotkeys category through this page - toolbar buttons can only be deleted from the toolbar itself."
You can turn off the hotkeys (without deleting them) from the hotkey list by clicking the checkboxes, which is the fastest way (but will leave them in the list, just turned off).
If you want to delete the toolbar hotkeys, double-click them to edit the toolbar buttons they come from, and remove the hotkey from the button via the arrow/menu on the right of the hotkey field.
Note that if the problem is you have hotkeys from a toolbar which isn't on, and you have your own replacement of that toolbar which duplicates all/most of the keys, then the above instructions aren't what you want to do.
Instead, go to the Customize dialog's Toolbars tab, select the toolbar where the hotkeys are coming from (usually Menu and/or Operations), and turn off Always enable this toolbar's keys in Listers.
The setting is on for the default toolbars by default because people often turn off the toolbars entirely, then wonder why Ctrl-C, Ctrl-V, etc. stop working.