Are you talking about the larger branch at the top of the picture? It's you call depending on your pruning strategy. Personally I'd leave it. I like to let mine grow.

I am talking about a. Lower branch with yellow on the end

This looks like normal dieback due to leaving a stub when cutting back a stem. The cut should be made within about one quarter of an inch above a leaf or node to cause a neat sealing of the cut. Al

It has now turned brown. Should I cut it off?

Cut it back to "within one quarter of an inch above a leaf or node."

Thank you. What is a node?

Suzy11, here!
Have fun!
I found it helpful. Hope that you do also.