Between Cholera and Polio, which disease cannot be controlled by killing the vectors
Both of these diseases do not have vectors, 
Cholera is a foodborne / waterborne disease and Poliomyelitis is spread through fecal-oral or oral-oral contact with an infected person.
They both only infect humans. 

Thus, both cannot be controlled through killing any vector. 

The best way to prevent Cholera is to avoid potentially contaminated food and water and follow proper sanitation practices.

The best way to prevent polio is through immunisation via vaccines. 

For more information: 

Cholera

Poliomyelitis