a discussion has come up at our local clix group of if you must clear your actions or is it optional? as always thank you all for your time

It is not optional.

CLEARING ACTION TOKENS (pg 8)
At the end of your turn, after you have finished
taking and resolving all of your actions (including
free actions that occur “at the end of your turn”)
and declared your turn to be over, remove all action
tokens from each of the characters on your force
that did not receive an action token this turn. This
is called “clearing” your action tokens.

No, clearing is not optional.

Page 8 of the 2013 rulebook:

It is not optional

CLEARING ACTION TOKENS
At the end of your turn, after you have finished taking and resolving all of your actions (including free actions that occur “at the end of your turn”) and declared your turn to be over, remove all action tokens from each of the characters on your force that did not receive an action token this turn. This is called “clearing” your action tokens.

Nowhere in the rules does it say you "may" remove the action tokens.

Thank you all, next question what if someone forgets to clear? do the actions stick or do they have to remove them?

Will your characters without tokens still be 'cleared' at the end of that turn? (for effects that care about it)

Depends. Did you both forget? Or did your opponent notice but didn't say anything? What exactly went down matters in these cases.

Depending on the circumstances, this runs the gamut from "Oops, my bad. Do you mind if I take that off now?" to deliberate cheating.

No. Clearing is the act of removing tokens.