Bug UGUI Canvas

use UGUI, I Create a UI Name A .set SetParent the Canvas Name B. Other GameObject Name C.
when I Destroy A. the A is B Child. this result is ok. Nothing exist in Memory。But, when I Change Parent to Other Object as C. A.SetParent(C). Now, Destroy A. Sprite has ManagedStaticReferences In Memory. whether this C is Canvas or Other GameObject.So. after Change Parent , What's the solution Can Clear ManagedStaticReferences

 

I Hav Find New Thing, I give The A AddComponent<Canvas>().When I Change Parent To Other Object.and Destory A. this result is ok. Nothing exist in Memory. I suspect Graphics referenced By Last Canvas.whether A is Change Parent. When Destory A, Can trigger Canvas dereference function。but A Change Parent. Not Find before Canvas. so before Canvas reference A Graphics