More demotivators-

Tell your managers who complained about them and what was said, in the spirit of 'divide and conquer'.  Keep repeating that same complaint year after year to keep it fresh in your subordinate's mind.

Trash the reputations of those who move on to greener pastures, in front of others, to show that you didn't need the person who left, anyway.

Scream, shout, yell at the person who made an error so everyone knows you really mean business when you ask for quality.

Berate people for not doing  assignments you didn't give them because their workload was already excessive.

Tell your professional staff that you 'know how to do their job' and could do it better, even when you haven't had that training.