How can I clear render cache or render memory

How can i clear render memory or render cache?
Maybe main reason is that my pc is short of spec.
but I have a trouble the follwoing.

Export mask channel is not correctly.
1th Render is almost correctly , but 2nd ,3rd is always different result
and mask result is incorrect. so I have to close D5 and restart for refresh.
but it is not good. if there is function of clear memory , I want to use it.

Sorry we do not have this feature yet, I will share this with our team.
Besides, could you share with me a screenshot of the mask channel issue? We will help you narrow down the issue cause first.


thanks for answer. But current project is clients design, not my design.
So , I can not upload these images.
if I come across same problem in the future ,
probably I can send yousome images and my data.

Mask channel often brign to me different result in heavy scene.
maybe main reason is my pc is not powerful, but this phenomenon is
does not appears in other rendering software.