Are you over 59 1/2? If not there may be a 10% penalty in addition to the tax. Money coming out of the pension will be taxable to both federal and state. Do you have adequate retirement funding from other sources if you take this money?
First, determine how much of your withdrawal is taxable. Ask if you have any waiting period associated with a withdrawal. Then ask how much you can withdraw without penalties. Ask if you have a minimum required withdrawal amount. Determine your withdrawal options and select appropriate tax witholding.
Pension withdrawals before the retirement age may mean a lower pay out over your lifetime. Depending on your state, you may have to pay income tax on the pension payments.