Ether 15:4

And it came to pass that he wrote an epistle unto Shiz, desiring him that he would spare the people, and he would give up the kingdom for the sake of the lives of the people.

He wrote a letter to Shiz. He asked him to stop hurting the people. He said he would give up being king if it would save people’s lives.

So he wrote a letter to Shiz, begging him to spare what was left of the people. He offered to give up the kingdom just to save their lives.