Is there any service/website that convert USDT to USD or EURO?
I want to minimize cost by not converting USDT to BTC/ETH before converting to USD/EURO.
Beware that it matters a lot where you want to get those USD or EURO "delivered". For example if you use a centralized exchange you will probably have to pay for the bank transfer.
BestChange.com is an aggregator where you will be able to choose from a good number of services to exchange your USDT to whatever you want. You'll be able to select on which blockchain your coins are and also select what kind of USD/EUR you want to receive.
You can
read more here or
use it directly.
Disclaimer: keep in mind that I am wearing BestChange paid signature. However, this doesn't make the service bad, it's actually great that you can read on Bitcointalk about it.