|Which effect do you prefer?|
Ignoring visible outcomesProbably the most effective way to demotivate employees is by ignoring the outcomes both of their work and yours, trivializing their achievements and demonstrating by example what you consider acceptable. You must acknowledge both the positive and negative results of any action. When your employees do things, that should be acknowledged. Flatly skipping over achievements will make them feed under-appreciated. Likewise, glossing over already existing detrimental effects of mismanagement will make them lose hope in your organization.
Highlight the positive effects of a person's work and they will do more of that.
Acknowledge mistakes you have made and open the road to continuous improvement.