In my opinion, you'd want to keep everyone in the campaign. Rather, I would have sales change the campaign member status if you're insistent they mess around with the campaign object. In our instance, we have added many custom campaign member statuses.
I'd like to better understand why you are wanting to update the campaign member rather than the lead/contact/opp object?
I agree with Paul. You should use campaign member status for this workflow.
Create a trigger or batch campaign to remove people/ pause people from Marketo send flow if SFDC campaign status = Pause/Remove
If you want to reactivate the send after some time, you can create another unpause campaign .
If you are using engagement programs then, you can pause and unpause people
If you are using standard drip program, you can either marketing suspend people temporarily or remove from campaign flow.