Use edge-select mode (Ctrl Tab 2), select that edge
Ctrl E and select Edge Loop
X and ‘Erase edge loop’
But … this may cause other problems (it might look too flat there). I notice that the author of the tutorial has a slight ridge there as well which may have been caused by “scaling slightly inward” on a convex curve. It gets covered up by a label so maybe it is not a big deal?