and
Phals are not among the group of orchids that need a "winter rest"...but water should be slightly reduced during winter for most orchids.
If the inflorescence (stem) is turning brown, go ahead and cut it off...that's not going to bloom again.
There is not a set "rule" for how to handle these...some folks keep it as long as it is green as there is a possibility of it blooming again. Others, such as myself, prefer to cut them back when the blooms are gone to allow the plant to put it's energy into becoming a stronger plant...the second round of blooms usually aren't as spectacular as the first were, anyway
Do you have any other orchids?
If you need help with anything, let us know