Disable built-in command
From Vim Tips Wiki
created January 26, 2004 · complexity intermediate · author Alfvaen · version 5.7
If there's a built-in key command in Vim that you find annoying, or that you often hit by accident, then you can disable the key by mapping it to nothing. For example:
:map K <Nop>
For "<Nop>", type the five characters as they appear (less-than N o p greater-than).
Of course, you can always
if you start doing C programming and want to instantly "man" things under the cursor again.