I’ve hand-washed clothes in the sink before. I just used regular bar soap, a basin of warm soapy water and gentle working on the parts of the clothes that tend to get sweaty + any visible soil. The more you let the soap do the work, rather than your hands, the better the clothes will hold up. Repeat the wash if the clothes are too dirty, my metric is if the water is too gross for me to bathe in after washing, wash again. Usually not necessary unless the clothes are really gross. Rinse in clean water. Wring out as much water as you can to reduce the drying time, just be careful not to stretch them too much. You can hang them over the back of a chair to dry, for smaller things I used the supports of the chair legs too. directing a fan at them makes them dry faster. It doesn’t have to be a powerful fan, just enough to keep some air moving over the fabric. I found it helpful to drape the clothes over the back of the chair and let one side dry, then flip it over to dry the parts that were in contact with the chair. Make sure they’re completely dry to the touch before you put them away so they don’t mildew. I’ll second the recommendation of putting them away ASAP and don’t leave them lying around when you’re not there. Parents are snoops and they usually suspect more than they let on. If you have ziploc bags or watertight containers you can also stash them outside the house, if you have a place that you can access securely. Going for walks through the woods helped me find places and gave me plausible reasons to visit them regularly.

P.S. I forgot to add, it may be a good idea to wipe the chair off before you put the wet clothes on them if you live in a dusty area. I may have unwittingly walked around with some dust stripes a few times 🙃