Yes, UNLOADING is a Scrabble word!

Letter values in Scrabble US: U 1, N 1, L 1, O 1, A 1, D 2, I 1, N 1, G 2.

Is it a valid word?

UNLOADING is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the labor of taking a load of something off of or out of a vehicle or ship or container etc.

Also: drop off, set down, put down.