There is now way to cancel your Constant Contact account via their web interface.
Chatting with a representative doesn’t work either.

The only way to cancel your Constant Contact account is by phone!

But it gets worse.

I called three times to cancel, and each time it says ’30min wait to speak with a rep’.

I finally gave in, and I’m waiting on hold using the time to voice my frustration.

Beware! If you have a Constant Contact account they will use every trick in the book to add friction to the cancellation process.

~ A Disgruntled Constant Contact customer