There is meant to be a button on the bottom right, I must have messed up the anchoring on GUI sorry. Once the jam is over I'll be posting an update to it if you are willing to hang around and try it again then! =)
No worries, I know the feeling - for some unhinged reason I made my entire game out of GUI elements when I don't have a strong grasp on GUI anchoring, so I just had to say screw it and force my game into a small window, lol. Definitely will stick around for the post-jam update!