Why did King George refuse to read the Olive Branch Petition?

Answer 1

John Dickinson drafted the Olive Branch Petition, which was adopted by the Second Continental Congress on July 5 and submitted to King George on July 8, 1775. It was an attempt to assert the rights of the colonists while maintaining their loyalty to the British crown. King George refused to read the petition and on August 23 proclaimed that the colonists had "proceeded to open and avowed rebellion."

Answer 2

About this, Wikipedia says the following:

"However, [the] petition was undermined due to a confiscated letter of John Adams. John Adams wrote a letter to a friend expressing his discontent with the Olive Branch Petition. He wrote war was inevitable and he thought the Colonies should have already raised a navy and captured British officials. This confiscated letter arrived in Great Britain at about the same time as the Olive Branch petition. The British used Adams' letter to claim that the Olive Branch Petition was insincere.[3]

Although the King discarded the petition, it still served a very important purpose in American Independence. The King's rejection gave Adams and others who favored revolution the opportunity they needed to push for independence. The rejection of the "olive branch" polarized the issue in the minds of colonists. It suggested that they could either submit unconditionally or seek complete independence by war."