So long as you don't enter a contract with a publisher that requires you to pull down old versions, you can do whatever you want with your work! Personally, I like to keep up free versions to attract more readers and then offer a more perfect paid copy.
Also as a side note, I'm not sure how effective this topic works as an announcement to your readers. Most of Tapas' reader-base are mobile-only and aren't even aware of these forums. The best platform to announce anything about your story is your story itself, in your episode descriptions and the episode itself.