In your turn, yes.so your models can still move if they choose not to attack?
Did this so many times with Stealers with the last Codex. You know, when our Anti-Tank was rubbish? Yeah.In your turn, yes.
In fact, you are almost always better off moving back, shooting, then charging the vehicle again as you get your bonus attack for charging again.
EDIT: This is against vehicles only though.
Walkers will lock you in combat just like regular models.