To 'un-set' the triggers,,,CArefully,,,w/o touching the front trigger,,,,pull the Rear trigger to the rear and HOLD it there. Then while still holding the rear trigger back,,pull the front trigger. That will release the rear trigger.
The rear trigger will let go under it's heavy spring tension so be prepared to hold it back so it does NOT spring forward and trip the sear.
That would fire the rifle.
Hold the rear trigger back once it's released (you will feel it so), and then carefully let the rear trigger forward till it stays static. It will remain in a neutral position and not touch the sear inside and the rifle will not rifle .
You can still fire the rifle by pulling the front trigger just by itself. It is a long and usually heavy pull. But is there to be used if the DST is not wanted.
This type of DST is called a double lever DST. The trigger fires from either position.
Some early (mostly muzzle loader & Target rifles) DST fire only from the 'set' position. These are called Single lever DST.