I formally accepted an offer for a PhD program a week ago. After visiting the school and meeting with my advisor, I was very happy with the decision. I had reached out to the schools I had not yet received an admissions decision from and had not heard back from them. Yesterday, however, I received an offer at a higher-ranked program for a fully funded (for 5 years) PhD.
In all honesty, I am not sure it is a better fit. However, I am interested in learning more about this new offer/program. Is it possible to retract an acceptance before April 15? How binding is a decision? What is the process to do so?