ABRUPT RESIGNATION

I was hired last Aug 2015 as a contractual employee the initial period was three-month contract. December 2015, because of the expected ISO audit next year I was willing to extend my services even without contract until February 2016. To give respect to the company I made a written endorsement that I am working even I am not formally employed to finish the reports until ISO audit hence my expected separation was February 2016 since I was also planning to start my review for board exam this Aug. 2016. I attended conference with the owner and my immediate head. They insisted that they will give me the Saturday off and half day off everyday to focus on my review. They also know that upon start of my review I will prioritize my review. Since the arrangement was enticing I signed a one (1) year contract which will be ending on Nov. 10, 2016. However due to the fast approaching audit I was always extending my office hours until 8:00 PM. It was not an approved OT but if I need to finish my reports I have no choice but to stay late as possible. I went out not earlier than 7:30 pm straight since January to April 2016. This greatly affected my review. I felt I was not enjoying the bargain of the Agreement that only convinced me to sign a new contract. Hence, right after the Audit I submitted a resignation letter. It is a usual process of the HR not to sign receiving copy of any resignation letter but they have filed my resignation together with the other resignation letters. Until May 10, 2016. I came home late again because of the problem of some of my subordinates.
I then submit a resignation effective immediately and I have no plan to continue anymore the contract that I signed.

I would like to ask if I can do the abrupt leaving of my post since the arrangement that is the only reason that made me sign a new contract was not observed? Do they still hold any right to charge me with anything?

Depends on the contract. No penalty clauses in the contract?