To cancel a registration, a letter can be emailed to bdc@dph.sc.gov or faxed to 1-803-896-0627, Attention: Renewal Clerk, referencing your South Carolina Controlled Substance Registration number and Federal DEA number, stating that you are requesting to cancel your registration due to whatever the reason may be, e.g., moving out-of-state, retired, no longer practicing your profession, or you no longer possess a valid South Carolina practitioner license.