Lay a piece of a paper grocery bag on your ironing board. Then lay the shirt over the paper bag and lay another piece of paper bag on top of the shirt. The iron can be set on a fairly high temperature. Set it on the bag, that is over the spot you want to remove. The heat from the iron should warm up the butter and transfer it to the paper bag. You may need to move the paper bag several times to transfer the butter from the shirt to the paper bag. This also works quite well with removing wax from places you don't want it as well.
becose he stol my shirt
wash it
You can try clorox clean up. But the stains probably won't come out all the way.
Wash it with washing machine or wash it with your hand.
You don't. There is no color left after the bleach.
Apply Nail polish remover
Sweat stains are tough to remove especially if you put deodorant on your shirt. However, these days there are a lot of good products available to remove these tough yellow stains. All you need to do is apply the gel directly onto the stain, wait 5 minutes and wash normally.
place some brown paper over the stain then go over it with an iron and the heat off the iron will bring out the fat in the butter soaking into the brown paper and then wash clothes as usual
Different stains require different methods of removal. Most stains, however, can be removed using a stain remover like Shout. You would need to spray the remover on the stain, rub it in a little, then launder according to the manufacturer's instructions located on the label of your custom t-shirt.
bleach the shirt
Usually if you just wash the shirt once it washes out. If not; try oxi clean's stain booster (color safe!)
Pour a half a can of coke on each armpit of the shirt. Let the coke soak in for about 3 to 5 minutes, but do not let it dry completely. Then throw the shirt in the wash using your regular laundry detergent.