You can hide it with Customize Visitor View options. Select Customize Visitor View from the view switcher on the top, then click Options on the orange customization bar. Select "Hide" next to Share button and click Apply.
But why would you want to hide it? All it does is it posts a link to your gallery; no photos are copied. Linking is the very nature of the Internet. It brings you visitors and potential new customers, why would you want to disable it? Besides, even if you hide it, it is still possible to copy the link from the browser and post it elsewhere.