Yes, you can stop future emails that are scheduled or automated. It is manual and you will have to click stop and there are two different ways to do this depending on how you sent out the emails:
1. If you sent out a series of emails through the standard email send page, you will see a section for "Emails Scheduled" on the contact's detail record page. In this section, you will see any emails that are scheduled to go out in the future and you can delete any or all emails for that contact here.
2. If you have added the contact to an email campaign and there will be automated emails going out to that contact as part of the campaign, then you will need to remove the contact from the email campaign. You can either do that in the email campaign area where you will see a list of contacts on the campaign and can remove or you can go to the contact detail record page and will see a section for "Email Campaigns". In this area, you will see any campaigns that the contact is on and you can click remove to remove the contact from the campaign.