Originally Posted by ZenFlyer

If by "liquidate" you mean transfer them in a lump sum to cash or another rewards currency, then I don't think so. However, there are some options for redeeming miles for things other than flights, e.g car rentals and hotels: https://www.aa.com/i18n/aadvantage-p...deem-miles.jsp

I note that if you are willing to share the reason you are seeking to do this, you might get some better advice here. E.g., is the issue that you or the miles owner doesn't fly anymore (so looking for non-flight redemptions)? Or are you concerned that the miles are expiring (in which case there are easy actions that can be taken to extend them)? Etc.