Go to...Eagle Dynamics\LockOn Flaming Cliffs 2\Config\Input\Aircrafts\select the aircrafts\keyboard and edit default.lua with notepad++
remove the two lines in the next line
--{combos = {{key = 'K'}}, down = iCommandPlaneCobra, name = 'Execute Pugachev\'s Cobra', category = 'Flight Control'},
Regards