Where do I go to withdraw my 401k

To make a withdrawal from a 401(k) you need to either contact the plan by telephone or sign onto the plan website.  If you do not have this information, contact the employer who provided the 401(k) when you were an employee.

Or do you need to enter a withdraw into your tax return?  You should get a 1099R for withdrawals. 

Enter a 1099R under
Federal Taxes
Wages & Income
Then scroll way down to Retirement Plans and Social Security
Then IRA, 401(k), Pension Plan Withdrawals (1099-R) – Click Start