What is the breaking down of amino acids into urea and uric acids?

The breaking down of amino acids into urea and uric acids is called Catabolism; from organelles to cells to blood circulation by amino acid transporters. Then, it goes to the liver and the kidneys in the degradation of the amino acid. After the urea cycle; it will then be excreted in the form of urea.

The breakdown of amino acids into urea and uric acids take place in the urea cycle, a biochemical process. 
Aspartate directly donates a nitrogen atom from the formation of urea during the urea cycle.
The argininosuccinate synthase reeaction links aspartate and citrulline via the amino group of aspartate and provides the second nitrogen of urea.