You will want to call the financial firm that operates the 401k plan for Lowes (you should be able to find the phone number on a recent statement) and request how to withdraw or rollover your funds.
Alternatively, contact the Lowes HR department and they will likely direct you to the financial firm. Typically, when you leave a large employer like Lowes, they will provide a document outlining your options for what to do with your 401K as part of that exit process ... but that paperwork can easily be discarded, making it hard to deal with your 401k later on.
"Cashing Out" can mean a couple of vastly different things. If you are looking for some extra cash to pay off bills or to spend in some other way, then it is a straight forward process as outlined in the previous answer. Please keep in mind that this kind of a cash out involves paying income taxes on the money you receive at your current tax rates in the year that you receive them. Both state and Federal. Add to this a penalty for taking the money out prior to age 59 1/2 (which is 10% for Federal taxes) and you get the idea. If for example you can owe 35% of the total amount you receive, the "Pot of money " you were counting on just got a lot smaller. Taxes should be paid shortly after the money is received, or the IRS may charge you interest and penalties for not making the payment sooner.
The other "cash out" option is not as much fun but is much better for you financially and that is to wait to spend the money and roil it over to an IRA in your name and postpone the taxes. The money grows tax deferred each year you leave it in the IRA and the taxes will be delayed until you are ready to use the money in the future.