I cannot find a way to unloc an item in KiCad version 7.02. It is not possible to select the locked item, so I cannot use the locking icon to swithc the lock off/on, though locking works OK.
I am running KiCad on Windows 10, but I have found another person asking the same quesion on Google, and he had tried on Ubuntu as wel, though no one has answered his question.