Yes, somewhat. You can't simply cancel your membership through your online account. Instead, you'll need to use Thrive Market's online chat feature to request a cancellation.
Ultimately, I decided Thrive Market wasn't for me, so I went the cancellation route right at the end of my 30-day trial window. The process took about 10 minutes, with the customer service rep offering me numerous discounts and offers to keep my membership.
However, in the end, my cancellation was processed and the membership fee was refunded within just a couple of business days.