Go to the Floor plan and select the section you want to edit (see the image below).
The selected section will become orange and you will be able to see the servers assigned to it, to edit the server zone (change the name of it or select other tables)
or delete it. After that, click on Edit.
Change the name of the zone.
Click on save and the name is changed (Dinner - Inside A is now called Dinner - Inside M)
Close the settings.