The coffee can be rubbed with lemon or vinegar first, then gently wipe with water, then wash with a neutral detergent, and the stain of coffee can be easily removed.
When the clothes are dry, apply the laundry detergent to completely cover the stain. Leave the laundry to rest for 5 minutes, allow the detergent to fully react with the stain. After 5 minutes, add proper water and wash it properly.
If it's a white shirt, try baking soda. The old coffee stains are wiped with a mixture of glycerin and egg yolks, then cleaned with clean water after a little dry. Or try the following collocation, decontamination more thoroughly
Glycerine + borax. Apply glycerin to the stain, sprinkle with some borax and soak in boiling water.
Glycerine + egg yolk. Use glycerine and egg yolk mixture solution to wipe, rinse after a little dry.
Water of ammonia/borax. Use diluted ammonia, borax and warm water to wipe the area of the coffee.
Ammonia + oxalic acid. Soak in 1 % ammonia water (40 ~ 50 degrees) for 10 minutes, wash with 1 % grass acid, and rinse with laundry detergent.
Use 3% hydrogen peroxide solution. Old coffee stains can be washed with 3% hydrogen peroxide solution and washed with clean water.