My bike has a X9 type rear mech, 2×10 setup with a bash and lower roller chain guide.

Question is, why? Do i need a lower chainguide with this setup?

Will i die if I ditch the lower guide?

Not essential, but your chain will rattle less and it is unlikely you will lose your chain with the guide on.

Short answer – No.
Long answer – Noooooooooooooooooooo.

You may drop a chain occasionally, or once in a blue moon depending on where you ride. This will not kill you.