Which is correct?

Deter to do something.

(Or)

Deter from doing something.

First let’s deal with the pronunciation of deter. The first e is like the I in bit and sit, and the second e is like the ir in shirt, bird and dirt. The stress is on the second syllable ter. The word deter is usually followed by from and not to. When you deter someone from doing something, you discourage him from doing it. You achieve this by making the individual realize how difficult the task may by or by highlighting the unpleasant consequences of performing the task. You do everything to ensure that the person no longer wishes to continue to do what he was doing.

Nothing you say will deter the students from joining the protestors.