It really is simple, rinse them under cold water once removed. Then when you are ready to wash, stick them in a delicates bag and wash them with your regular load.
We suggest you use the sunshine to dry the underwear. The UV will help to sterilise and kill any residual bacteria and odours.
You can use a dryer on low heat if you prefer. Be sure to keep the washing and drying temperature under 80℃ and don’t use any fabric softener or bleach on them!