CORRECTION
I meant how much at age 72 can I withdraw without penalties and with same employer?

No picture

You may have already entered a "withdrawal" penalty situation. At age 70.5, you should have started taking money out of the 401k account. This is called the "required minimum distribution" and is based on a "life expectancy table" published by the IRS. For general information, you should go to this website: http://www.irs.gov/retirement/sponsor/article/0,,i d=151926,00.html and then you should read IRS publication 575. It's available as a PDF at http://www.irs.gov/pub/irs-pdf/p575.pdf, which you may want to print out.

Without more specific knowledge, it appears that you may be subject to penalties for not starting the distributions earlier. You should also be aware that there you will owe income taxes on distributions from the 401k if they are large enough or add enough to your other income.

Your plan administrator is/was required to notify you about making timely withdrawals. It is important that you begin this process immediately by contacting the administrator.

However, if you have a self-directed 401k it is very likely, at this point, you may need expert legal advice from an IRS-qualified attorney. There will be some cost to you for the legal fees, but it may save you quite a lot of money to begin the process properly.