There are many options for correction. If the cause is due to the teeth or gum tissue then you should visit the dentist who can investigate and offer treatments to address these causes.
For gumminess caused by overactive muscles, injection of Botox into the hyperactive muscles weaken them. This corrects any asymmetry and excessive gingival display to eliminate gumminess. If the cause of your gummy smile is a thin upper lip, consider lip enhancement with hyaluronic acid dermal fillers. These can provide a fuller lip which reduces the appearance of gums when smiling.