Save Spirit by H.A. Wills

Supernaturals are real, and seventeen-year-old Callie is the strongest of them all. As a Spirit Witch, she is a member of an ancient sect of witches that were wiped out millennia ago. She not only has control over the four elements, but also life and death itself, and she’s been tasked with maintaining balance within the mortal realm. No pressure.
At least her magic is finally unbound, so life should get easier and have a lot less exploding trees. Except, nothing is ever easy for Callie. Her magic wasn’t the only thing unbound. It’s getting harder to stay “just friends” with the guys—especially since they all seem interested in tasting her chapstick. Not to mention Felix, her incorporeal best friend, decided to reject his door to the afterlife. This means he either blinks out of existence or Callie figures out how to use her powers to break the one natural law all supernaturals can agree on:
The dead need to stay dead.