Remove users from updats thread

[#1]

Once someone is included on a Workfront updates thread, they are there for life. We need to be able to remove people who are no longer on projects or who were tagged in by accident.

[#2]

Will be raising this idea up through our organization for votes. This is NEEDED sooner rather than later as it is reducing effencies for workers and leaders in the system. They get added into an update for one small piece of a task and then don't need to be on the rest of the chain, but others need to stay involved in the ongoing chain. Please don't suggest starting a new update! Create the functionality to remove users from an update!

[#3]

This has been an ability for a while now as I'm sure you've seen, @SarahMc3 . @jon_chen can you mark this as Delivered when you're back from break?