This guide is for those who are interested in doing it this way, and who are qualified for working with coolant hazards. If you're not interested, no need to say it. Thank you.

1) Remove the nozzle as you always do and throw it into the barge

2) Grab one of the coolant canisters located next to the nozzle

3) Without letting go of the canister, smash it against the hull of the thruster

4) The canister is now leaking coolant. Place the canister next to the 4 fuel lines and freeze them (don't worry, this will not damage anything)

5) Make sure all four fuel lines are frozen next to their cutting points, then throw the coolant canister into the incinerator

6) Melt the four fuel lines' cutting points with the stinger (unless one isn't frozen anymore, in which case return to step 2)

7) All four fuel lines are now safely cut, you can access the emergency cut off valve without the risk of getting burned :)

8) PROFITSSSS