Default Return to T-Mobile Stock M8

My rear camera is taking washed out pictures that are blurry. I have wiped it and it still is blurry. I think that there is some moisture inside the lens. I want to return this phone back to T-Mobile. How do I bring it back to stock?
HTC One (M8)
T-Mobile Note 2
Nexus 7
G2, G1 Bronze, G1 Black,