A file previously deleted is still taking up space

A game (Paladins) i used to have dowloaded is still taking up 15GB of space. it doesnt appear in; Trash, spotlight search or applications folder. However it does appear when i go to 'About this mac'->'Storage'->'Manage'->'Applications'

its the fist one in the applications section as it is the largest file, you cant click delete on this file the button is greyed out. what can i do to get rid of this and claim back that 15GB of space? thanks