What can i do to eliminate lower back pain during yoga?

Modify poses: Assuming your back pain etiology is clear, and you are comfortable enough to stretch your body with yoga, then modify the poses (asanas) to minimalize pain yet still engaging your body to stretch. Bolsters, folded blankets, blocks, all of these aids can allow you to be in a pose comfortably and remain in the pose long enough to obtain the benefits desired.

Hip extension: Work on hip extension and hamstring lenght work with mckenzie therapist.