Where can you find it: Under Content, you can see the labels

To explain how labels work, we have two bots in the same workspace. One of them is Whatsapp Bot, while the other is Omni Channel.

When you create a label, you can access it in all bots that share the same workspace. 

How you can use in sub-flows:  
In action node -> basic action -> add and remove label.

You may now view these labels in Live Chat. 

For example, we have created “new customer” label, and it’s shared across all the bots in the same workspace, and you can create the filter like the screenshot below

Once it’s saved, you can save this as public or private segment, and then your team can access these contacts easily from the left sidebar.

That’s how you can use the labels with global contact add-on.

This option allows you to remove all labels inside the flow builder.