United States Territorial Relief Act of 2018 This bill establishes a process under which Puerto Rico and other U.S. territories may terminate certain debts if they meet eligibility criteria. The bill allows territories to terminate their public, unsecured debt if they meet two of three criteria: the population of the territory has decreased by more than 5% over 10 years, the territory received major federal disaster assistance, and the territory's per capita debt exceeds $15,000. The bill also provides funding that a special master must allocate to certain creditors whose debts were discharged under this bill.