Ok first you pack your "sex" doll in your car load it with water go to the nearest lake [if you don't have one booze it up] and drop it off for a while, then after 1 hour come pick it back up
You need to know the material it's made from to pick the appropriate method to sanitise it.
Source: Someone who discovered that they'd accidentally bought styrene shot glasses for thinning and mixing cellulose paints for an airbrush and had a bad time.