Name 1 method by which patients should be encouraged to dispose of unused opioids

The answer is to take back program or DEA-designated drop box.  

In order to prevent misuse and diversion of opioids, the US DEA (Drug Enforcement Administration) suggests abolishing expired or unused opioids or making patients to drop off medicines to a take-back program or a DEA-designated drop box.  

At present, only a DEA-designated official can dispose of and receive a controlled substance. The take-back programs like the DEA's semi-annual National Prescription Drug take-back day, are the ideal ways to dispose of unused or old opioids.