Retirement tax questions

I am OK to pay 6% Penalty the First year  , I am planning to  file my 2016 Taxes by 18th April  . Can i get the excess withdrawn after that . I dont have much money in my HSA , and plan to use all that money for medical expenses in 2017 and then close the account ( would have no HSA after that). Want to Withdraw only if i cant finish that money . Can i do this? I dont want to file Amended Tax return the 2016 Year.