Stultify (verb)

1. To cause (someone) to become or to seem foolish, incompetent, or ineffective.
2. To render (something) null and void or ineffective.
3. To inhibit or impede the development, progress, or function of something.

Origin:

From the latin stultus, meaning foolish or senseless.

Examples:

1. The lack of training stultified his efforts to perform the job.
2. The constant criticism stultified the employee's confidence.
3. The new rules stultified the company's ability to compete in the market.
4. The constant interruptions stultified my concentration.
5. The constant changes in the company stultified the employee's motivation.