Sounds like you want a Batch Campaign » Flow » Change Data Value Unsubscribed = true.
The more detail you provide in your posts, the more we will be able to help (asking complete questions is preferred).
It would depend on how you have identified all the emails that you want to unsubscribe.
If you have a list of email addresses you want to unsubscribe and they are already in your marketo system, you can identify then in a smart list or import them in a static list and perform a single flow action and set unsubscribe to true.
If you are selecting the emails via some filter criteria, you can do so in a smart list i.e., member of program is tradeshow, or member of static list, or country is not USA, and perform a single flow action and set unsubscribe = true.