There was a community discussion almost three years ago about the fact that the manual unsubscribe feature wasn't working in Chrome back then:
Well, apparently the issue still hasn't been fixed because I can't manually unsubscribe a contact in Chrome, even when I go incognito (so it's not an issue with a plug-in or extension like the Constant Contact employee tried to claim that it was). Of coure, if I go into Internet Explorer (yuck), everything works just fine.
When is Constant Contact going to support Chrome? This is ridiculous, and it's way too critical of a feature to not have it be having work across all browsers and platforms at all times. Please get this fixed once and for all. It's ridiculous.
I'm so sorry you've been experiencing difficulty manually unsubscribing contacts in Chrome. I did see you had an email interaction with us earlier this year on the topic. I checked into it, and I am not experiencing trouble getting the unsubscribe drop-down option to work in my session of Chrome, which leads to believe this may be a plug-in or extension related issue. Have you tried running Chrome in "incognito mode" to check and see if it works out there? Here is a handy FAQ/Tutorial that may additionally help with troubleshooting these sorts of issues. If you've exhausted all of those resources and it is still happening, don't hesitate to reach back out here, or give our support a call. Our hours and numbers are listed here.
Thank you for reaching out to us through the Community! I apologize that you are experiencing this issue. I will like to look into this further for you. Could you please email us at social_support(at)constantcontact(dot)com with a reference to this post and the name of the contact that you are trying to unsubscribe from your database? Thank you!