No.  There are no initiations to become a sannyasin that are required in order for you to practice yoga.  There are many styles of yoga to practice.  A class entitled Hatha Yoga does not aline itself with any particular lineage of any Yogic Master.  Yet, even if you see a class called Kripalu Yoga, Sivananda Yoga, or Integral Yoga you are not required to learn the teachings of the Yogic Master for which that style is known.

   So, if this is all that is holding you back, come on down, our door is open.