Hey Alan,
Go to the All Macros group and search for 'switcher'.
When you find the right macro disable it.
I believe there's not a convenient method to do that, but it can be done.
Disable all the relevant clipboard switcher macros, and run this in the Terminal:
defaults write com.stairways.keyboardmaestro.engine MaxClipboardHistory -int 0
You can restore the default (100) by deleting the preference:
defaults delete com.stairways.keyboardmaestro.engine MaxClipboardHistory
You can change the max by changing the zero in the first one to another integer.
I use LaunchBar myself, but I keep KM's clipboard switcher enabled ā because I can have more items in it ā and the search is sometimes more accurate than LB's. So I usually start with LB's history and move to KM if I don't find what I want.
-Chris