Yes, TERMINATE is a Scrabble word!

Letter values in Scrabble US: T 1, E 1, R 1, M 3, I 1, N 1, A 1, T 1, E 1.

Is it a valid word?

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

bring to an end or halt
have an end, in a temporal, spatial, or quantitative sense; either spatial or metaphorical
be the end of; be the last or concluding part of
terminate the employment of; discharge from an office or position

Also: give notice, give the axe, send away, force out, give the sack.