If you want to remove it, why is it wired to the Add in the first place?
I think you should describe the whole process you are trying to accomplish. Please do not make us guess.
It's a project training of my college. My tutor ask me for adding the AWGN then remove it,just that.
Then it seems to me that you need to get clarification from the tutor about what is intended.
Are you to simulate or implement various noise reduction techniques? Which ones? How will the performance be measured?