You cannot withdraw your Tether balance. They literally do not allow that. The best you can do is get an intermediary coin that some places might let you change into cash or another crypto.
As I understand tether allows direct conversions to fiat, you just need big enough amount. Also it is very easy to convert to bitcoin, which is very easy to convert to fiat.
The minor difference is that you can withdraw your balance from banks, but you cannot redeem Tethers to what it's supposed to be backed by: U.S. dollars.
Hundreds of millions of people do this every day around the world without issue, because this is a solved problem.