We can configure mass editing from Menu: Settings -> Mass Editing.

From here you can create a new record for mass editing.

Select a model and configure fields for mass editing.

After that click on "Add Sidebar Button".

By clicking on "Add Sidebar Button" action is created for the selected model. With the help of that action, we can update or remove the fields values which were configured in mass editing configuration.

The user can remove the action by clicking on the "Remove Sidebar Button".

Go to the model/object in which mass editing is configured (ex. Partner).

Select records on which you want to edit or remove the value(s) of the fields.

You can see the "Mass Editing ()" option in the action bar. Select that option for mass editing.

The user can set or remove the value of the fields which were configured in mass editing configuration.

You can see the mass editing changes in customer tree view..

You can see the mass editing changes in selected customer