Several schools in the Atlantic Coast Conference (seven or eight depending on who you ask) have been dissatisfied with their status in the league, including Clemson Football.
The contract preventing most of them from taking action is the Grant of Rights, which gives the league the rights to their television properties, namely their home games. If a team were to leave, all revenue from their home games would revert to the ACC, not the school.
It would be possible for a institution to negotiate an exit from the GOR, but it would be expensive. The current GOR does not expire until 2036.