Corporate cultures are created by those who founded the group, and it is upper and middle management the can change it. Those who start a company with visions, beliefs, systems and values.
The word "culture" may be difficult to understand precisely because corporate culture is a "multitude of interrelated processes and mechanisms" (Peter Bregman).
In general terms, the culture of a company is set by those at the top of the corporate structure so it must look to the leaders for the solution to a culture that is out of line with expectations or visions.
Performance reviews and training programs define the firm's expectations. Financial reward systems reinforce them. Memos and communications highlight what's important. And senior leadership actions ... emphasize the firm's priorities. (Peter Bergman, Harvard Business Review)
Leadership which models excellence is setting a positive culture for the company. Some ideas for change on a small scale include asking for and heeding employee feedback, addressing concerns as they arise rather than letting them fester, and routinely recognizing (rewarding) the positive behaviors a company wants its employees to emulate.
The first step toward change is that leadership should target and define the cultural change they want to effect and begin to instill this new cultural norm by what they do themselves. One concrete example is offered by Peter Bregman of Harvard Business Review. He suggests that if the change that is wanted is less perfectionism and more speed, then management should send their email messages with the typos still in them.
The second step is to find people in the firm who are already perfoming in a way that illustrates the desired change. These people and their behavior can be publicized and praised to begin a process of applying peer pressure. Bregman asserts that over time, the changed "stories" coming from management and from employees will build a momentum of peer pressure that will forward the desired corporate culture change.
In keeping with peer pressure, a group of employees determine to effect a change can create a force of peer pressure in their own department or team by performing according to the new norm. It is important for these groups to be in accord with not in opposition to management's vision and expectations.