Probably not. As well as being marked as a super admin you would also actually need to be an admin otherwise you wouldn't be a proper admin.
If it's your site and you have full access to the hosting then you could edit the xf_admin table and switch his user ID for yours. Never ideal but it should get you back in, and then you can make sure you're more careful about who you make super admin in the future.
You will need to set is_admin to 1 in the xf_user table too.