All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
If the situation of the organization to which you were elected is as evil as you have mentioned, then it is forbidden for you or for any other Muslim brother [or sister] to remain as a member in it. Staying as members in such an institution is increasing their number, luring and deceiving other Muslims, and giving a wrong impression of Islam, as if Islam does not object to such forbidden activities that the students are engaged in, since some Muslim students are members of their governing board. Just by remaining in such an organization, you are helping them in spreading injustice and mischief, and propagating for it even if you are not really participating in their forbidden activities. Allaah says (what means): {Help you one another in virtue, righteousness and piety but do not help one another in sin and transgression. And fear Allaah. Verily, Allaah is Severe in punishment.}[Quran 5:2] By electing you to such a board, they are in reality exploiting you to propagate their mischief.
For more benefit on the relationship between a Muslim and a non-Muslim, please refer to Fatwa 88293, and to Fatwa 84777 about studying in a non-Muslim country, and to Fataawa 84281 and 87469 about studying in mixed schools, and finally to Fatwa 86405 about residing in a non-Muslim country.
Allaah Knows best.