Labels are an informal way for you to categorize your objects, such as challenges, objectives, capabilities or initiatives, so that you can apply a filter and see only the objects that match your selected label. You can read more about how to apply labels in this article - Using labels to tag and filter initiatives.
If you need to rename or delete a label that is assigned to lots of objects, then you can do so in two ways;
Rename or delete a label for an object's properties panel, one at a time; or
Manage all labels in the Settings properties, which will automatically apply a bulk update to all objects.
Managing Labels for the whole canvas
Open the Settings window by clicking "Settings" in the top right corner. Click on the Labels tab to see all labels (as shown below).
When you rename a label in the Settings, all corresponding labels assigned to your challenges, objectives, capabilities or initiatives are automatically renamed.
When you delete a label in the Settings, all corresponding labels assigned to your challenges, objectives, capabilities or initiatives are deleted.
Note that you cannot add a new label in the Settings window because a label must be assigned to a challenge, objective, capability, or initiative directly.
Retaining Unused Labels
The default is to automatically delete unused labels. When a label is untagged from an object, such as a challenge or objective, and it is no longer tagged with any other object, it is automatically deleted. This automatic clean-up approach ensures the list of labels is always the one being used.
Now you can choose to retain unused labels by selecting the "Retain unused labels" checkbox in the Settings window.