If you've published ebooks through Smashwords and don't want them for sale anymore, you'll need to contact your publisher and let them know you don't want to sell through them anymore. And double-check that they've removed your ebooks from the site. Remember though, this is publishing, not the stock market, so patience may be warranted.
Adding your ebook through pubit will need to be a separate action on your part and you'll need to load all the data yourself. You're effectively switching publishers. And gaining all the royalties.
I have two books on smashword but only sold 2 copies in several months. Having said this,it does not hurt to have a book listed on multiple platforms, after all you want EXPOSURE, right? It is not likely that you will be invited on Oprah's book club, so any exposure helps! If you list with Amazon kindle and Pubit directly your book will not be used from the smashword distribution. But other sites, as remote or slow they may be....
I hope this helps
Andras Nagy (Ancient Wisdom Publications)