Yes, UNBLOCK is a Scrabble word!

Letter values in Scrabble US: U 1, N 1, B 3, L 1, O 1, C 3, K 5.

Is it a valid word?

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

clear or remove an obstruction from
play the cards of (a suit) so that the last trick on which a hand can follow suit will be taken by a higher card in the hand of a partner who has the remaining cards of a combined holding
make (assets) available