After you’ve worn your period underwear, rinse them with water.
You’ll see some blood come out, but it’s okay - it’s your blood.
Throw in the laundry bag until laundry day.
Or rub with some soap, hand wash them and hang them up to dry or low tumble dry.
Or… if you really don’t feel like rinsing in the basin under water, you can either rinse them in the shower with you or throw them straight into the laundry with everything else.