This is stated in an order of Bulgaria's Minister of Health Kiril Ananiev

As of June 18, the 14-day quarantine for those arriving in Bulgaria from Iceland, Norway, Switzerland, Liechtenstein, San Marino, Andorra, Monaco and the Vatican is lifted. This is stated in an order of Bulgaria's Minister of Health Kiril Ananiev. 

The directors of the regional health inspectorates have been ordered to revoke the issued prescriptions for quarantine of persons who arrived in Bulgaria from Iceland, Norway, Switzerland, Liechtenstein, San Marino, Andorra, Monaco and the Vatican in the period from June 5 to June 17, 2020.