Start by requiring people to be at work from 9 am until 5 pm from Monday through Friday even when they are working significant overtime. This is especially important when someone has to work through the weekend to fix a problem or install a new system. There are other ways to use rigid rules to drive technical people away. For example, never give an extra day or two off to people when they have been working extra overtime. It is also fun to focus on things like minor dress code violations.
Technology is a fast moving field and skilled technical people know that.
Therefore, do not encourage technical people to remain current in their field by allocating budget money for professional training. You should also avoid sending technical resources to relevant conferences. These sorts of things make people feel valuable. You should also avoid the idea of offering to pay for even a portion of college study relevant to a person's position. When people keep learning they do their jobs better and that benefits the company.