Memories of Holdenshire.

What are you using, is it the spell Produce Flame?

sacred flame cantrip

Okay, so basically, you produced a flame in your hand to light the area. You can also, as part of casting this spell or in a later round, also perform a ranged spell attack, which means that you can throw the flame at the goblin using your WIS mod.
Of course if you do so right now, you'll make your ranged spell attack at disadvantage because you are in melee with your target seeing as since this is a surprise round, you would have performed your action which would meant that you cannot also move. You could move away from the goblin next round (a normal combat round) to throw your flame it it with no penalties, but doing so would provoke an attack of opportunity from it since you're exiting a threatened area.
Another possibility would be to attack the other goblin instead...

right I forgot about the disadvantage because close quarters. Would I also attack at disadvantage if I'm attacking the other one? I know the range is correct but my original target would be standing right next to me?

I thought the answer was no, but yes, if you are within melee range of an hostile creature, you make ranged attacks at disadvantage even if the target of the ranged attack is not the creature you are in melee with.

Okay, no problems. And yes, your math holds up.

edited, thx.

The question was aimed more at Harsk and Garbuffel who dealt the finishing blows as when you reduce a monster to 0 HP, you can choose to kill it or knock it out.