Many managers struggle to delegate responsibility at the beginning of their management careers, and in extreme cases some never learn to delegate.
The problem with not delegating is that your management style cannot scale: it is unfeasible for example for a CEO of a large multinational to have reached that level without mastering the science of delegation, as they simply cannot directly manage all aspects of such a large organization. Put simply, not being able to delegate will place a cap on your management career.
In my experience, the best delegation technique is to identify the natural leaders in your group, who are those that already command respect with their peers. Next, you need to assess their judgment under situations that you would like to delegate responsibility to them. It may be as simple as asking them "What do you think we should do here?", and if their answer matches the optimum outcome enough times, you will build enough trust in them to execute on those judgment calls the next time around, without your direct approval. An added benefit is that you earn their respect, as they see you are asking for their input and trust their judgment.
Over time, as you increase the amount of senior people reporting into you, you are able to expand your reach and be more productive by simply providing soft guidance rather than direct control on every detail. Trust your senior people, and learn to ignore the urge to micro-manage or to do the task in question yourself, because neither of those approaches will scale beyond a small team.