Personally I would just be patient. When a bamboo changes it's leaves they will turn yellow just before they are replaced with new leaves. Pruning it may destroy new leaf buds. Plus pruning branches will not grow back. Give it time to see it may just re-leaf out I've had bamboo that lost all their leaves and I thought they were history but a little time and patience paid off because they completely re-leafed out and now they are beautiful again.

I agree with gardener1...you will not help the health or the permanent appearance of the plant by pruning now. You say "half" is yellow. Does that mean one of two culms has turned yellow or what? If so, it could be the natural cycle and you have a dying culm (they last about 7 years on average), which could be completely pruned out after several months if you get no re-growth.

Bamboo generally do best in the ground, not indoors, even if you do take it outside periodically. If the air is dry inside this time of year, that could explain why it is not doing well. Do you mist it? And why don't you plant it? Is it not hardy enough?

Also, what species is it?

Only because you state that it is planted in soil, is what you have lucky bamboo?