Cancel is the wrong term, I'm assuming that you mean, stop making contributions, the answer is yes, I also assume that you mean that you want to take a distribution (cash out). If you take your money out it is called distribution. A distribution made prior to 59 1/2 is penalized at 10% and taxed as ordinary income. In other words you get screwed big time. HOWEVER there are such things as a qualified distribution, Google qualified distribution and select IRS.gov and you will find a publication concerning 401k qualified distributions. Good luck