Lord Shiva, is called the God of destruction. But what does He destroy?

Lord Shiva, is called the God of destruction. But what does He destroy?

Now, tell me, said the yogi, how am I supposed to destroy the world?
By opening your third eye, wherever you shift your gaze then, turns to ashes.
Mythologically, said the yogi. Now, listen to the philosophy.
At the personal level, the destruction of illusions, makes the meditator enlightened. This is the opening of Gyan Chakshu, this is the whole path of the yogis. The gaze of the discriminating mind destroys wrong previous concepts and illusions. Whatever scriptures such a man reads, he interprets rightly, whatever situation he encounters, he understands. The mind of spiritual discrimination destroys falsehood and delusion.
At the transpersonal or cosmic level, I am a paradox however. My capability is to destroy the whole cosmic play. But, if I use only half my power, to destroy the destructive processes themselves, verily, I become the course for expansion. So using half your power doubles your strength. It also takes double your strength to use half your power. Meditate upon this, said the yogi.
{From The Yogi and the snake }
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The great significance of destruction is primarily in the end of an individual ego and therefore merger into God consciousness. This is the philosophy.
As far as mythology is concerned, shivji holds the power to destroy the Universe he Himself created. but he does not do that. He weeds out the unwanted parts, just as a loving gardener would...
Shivji is the only God , who is, indeed prayed to 'take away ' things, not just supplicate them. He is 'Hara' the taker away.
So too, He is amazingly prayed for taking away things also.Take away pride, selfishness, greed, hatred etc. Aum Namah Shivaya!!