Removal of the face paints used by Face & Body Art by Larissa is really easy, because it's not actually "paint." It's makeup! So... baby shampoo, makeup remover, soap and water, or baby wipes will all work to remove it easily. You won't need to scrub at all.
While children have been heard saying, "I'm going to leave my face painting on and wear it to school tomorrow!" that's not suggested. It shouldn't cause harm, but while the makeup is hypoallergenic and safe, just like mom should wash her face before going to bed, the kiddos probably should too.
Temporary tattoos can last anywhere from a day to a week, depending on several factors, including the part of the body, the model's skin type, other skin products used, and how much they're rubbed. To maintain a temporary tattoo for the maximum length of time, your best bet is to have it done on a body part that doesn't move a lot. One on the back of a hand will fade a lot faster than one on a bicep. Dry skin will maintain them longer than oily skin. And lotions decrease the retention time.
If you want to keep them on, do your best to avoid moisturizers and oils on the area, and when you wash and dry, don't scrub or rub the area, just blot.
The opposite is true if you want to remove a temporary tattoo, of course. Baby oil will asssist in removal, as will lotions or rubbing alcohol, especially alcohol with a higher concentration than 70%.
To maximize the longevity of your henna tattoo, you'll want it placed on thicker skin, like the palms of your hands or soles of your feet. On one person, a henna tattoo on an ankle can last three weeks while the same person's henna tattoo on a bicep could fade in one week. Once you've got the henna tattoo, moisturizing and using baby oil will actually help maintain it. Exfoliation is the enemy of henna.
There's no real way to remove henna; it just needs to fade. You can speed up the process, though, by exfoliating regularly.