If the enemy unit is left with 2 might, can I play the Glist and tap to kill?

No — not by itself. The List gives the unit −2 Might, which just drops a 2-Might unit to 0 Might. A unit at 0 Might doesn't automatically die; it only dies in cleanup if it has damage marked on it (Rule 142.4.b — lethal damage is non-zero damage ≥ Might, so a 0-Might unit needs at least 1 damage marked).

So: if the enemy unit has no damage on it, it survives at 0 Might until end of turn. If it already has any damage marked (even 1), then yes — reducing it to 0 makes that damage lethal and it dies in the next cleanup.

Two extra notes: you must have named that unit's tag when The List was played, or it's not a legal target; and the −2 lasts "this turn," so the unit returns to 2 Might afterward if it survived.