The best option is to dispose of it if you no longer need it. You can contact your neighborhood hazardous waste facility since lighter fluids are toxic. For inappropriate disposal, some states levy steep fines. The facility may require you to drop off your used charcoal lighter fluid, or they may arrange for a pick-up. There may be instructions for safe disposal on the label of the lighter fluid container. Asking the manufacturers how to get rid of lighter fluids over the phone is still an option.