On hover - that means it's your theme is forcibly inserting the button when it ought not to do that. If I had to guess, I'd guess you bought the theme at ThemeForest.
Oh ... just looked, yep, you bought it at ThemeForest! Not to knock ThemeForest, but just to point out that 99% of the time when people contact us about theme problems related to WooCommerce their theme came from ThemeForest; where sales are high and quality is typically only so-so.
Anyway, use this CSS to hide it:
.action .add_to_cart_button { display: none !important; }