Lord Shiva is considered the destroyer. What does he destroy? Destruction is mostly seen from the point of view of being fierce in nature, cruel in disposition and desensitized in action. Yet from another point of view, Lord Shiva's destruction is an integral part of universal laws. Nothing in this world is eternally existing. Every thought, thing, idea and relationship appears at some point of time (creation), stays for some duration (maintenance) and eventually disintegrates (destruction). There is nothing in this world which does not go through these three stage of realities. These three aspect are delineated in great detail in the Vedic literatures and are represented by Brahma for creation, Sri Vishnu for maintenance and Lord Shiva for destruction.
Thus Lord Shiva’s role as destroyer plays a fundamental part in the laws of universal creation. Furthermore, this destruction is more than simply fierce or cruel.
Lord Shiva could certainly destroy auspicious things, but He can also destroy those things considered inauspicious.
In other words, He destroys both good and bad. And ultimately as time he destroys all.
The practicing Yogi, while following yogic dharma, sees these principles even in his daily activities. The disappearance of disease happens because Shiva Shakti becomes activated in one's yoga practices. The yoga practitioner may also start experiencing his mind becoming equipoised, his ego becoming more and more transparent or his body getting thin. In this way a Yogi sees utility in destruction; such vision is the aspect of seeing Lord Shiva. Eventually the yogi's own yoga practice and his body becomes destroyed by the power of time. Such destruction is also the act of Shiva tattva.
In Hindu philosophy, all the Puranas, itihasas and other literatures demonstrate the Rudra Shakti aspect being used by the warrior class.
These people invoke the power of destruction by reciting 'Har Har Mahadeva.' The warrior cannot attack unless he has the destructive force within himself, and this power and ability to destroy is the force of Lord Shiva.
By the power of time, that which was existing falls or disintegrates, giving rise to new things and eventually over time these new things grow old and get devoured by fresh things.
Imagine if no one died, fruits did not rot, vegetable remained as fresh as ever, humans didn’t grow old, and ever green youth became reality in this world. Such a phenomenon would certainly cause a great disturbance in the universal cycle. Therefore, Lord Shiva always invokes destruction to create balance. Let the destructive force of Lord Shiva always be active at the appropriate time so that we can always experience new creation.