The practice of Yoga is to finally achieve total cessation of all activities/fluctuations of the mind(cognitions, emotions etc) in order to manifest pure consciousness which is otherwise occluded by all of this. So yes, at the final stage of Yoga all emotions are gone. However, in the beginning stages of Yoga one cannot deny any of their emotions, but must acknowledge them and recognize that they exist. A space must be created where one is able to see themselves as experiencing an emotion e.g. “I am now experiencing anger”, rather than seeing themselves as identical with the emotion e.g. “I am angry”
In this way you will begin to recognize that you(the I) are not the same as any of the emotions you witness. They are just like passing seasons, changing scenes. Whatever emotion comes you will be able to see it in this way:
I am now experiencing anger
I am now experiencing lust
I am now experiencing pride
I am now experiencing jealousy
The same is true for any cognitive state you are experiencing:
I am now experiencing a memory
I am now experiencing imagination/hallucination
I am now experiencing faulty thinking
I am now experiencing correct thinking
I am now experiencing an altered state of consciousness
Yoga arms you with a vocabulary to help you identify exactly what emotion or cognition you are experiencing to help you monitor your thoughts, similar to thought-monitoring in CBT.
When you experience your emotions in this frame you are still going to feel the emotion, but you are not going to feel it as strongly as you would if you were in the frame of “I am angry, I am sad, I am jealous, I am scared” This is because the latter frame identifies yourself with the emotion and thus the emotion hits you a lot more strongly and lasts much longer(even years) On the other hand, when you recognize it as just another change of state you are experiencing, its affects are only momentary and it soon passes. If you experiencing anger, you can tell yourself:
I am now experiencing the emotion of anger. It is a disturbing emotion and I would prefer not to experience it, but it does not always have to be this way and most of the time I am not experiencing anger. It will soon pass and I will be back to normal again.
By saying this to yourself when the emotion of anger comes you instantly put yourself in the witness frame and reduce the power and time of the anger to affect you. Everytime you repeat this when the anger comes like a mantra, you will weaken the power of anger to affect you gradually, until it is all but gone.