You have changed your mind about the iron-on letters that you applied to your shirt, and now you want to remove them. Don't try peeling the iron-ons off without treating them; that will ruin the shirt. You may be tempted to throw away the garment in this situation because you don't know how to remove the iron-on, but you don't need to do that. The shirt can be saved with some heat, glue remover and a little patience.
Lay down a thick towel on a non-flammable counter or set up your ironing board. Pre-heat the iron to the medium heat setting; hotter than this will scorch the fabric.
Turn the garment inside out, and place the thin cotton cloth over the iron-on letters. Place the garment on the towel or the ironing board.
Run the iron back and forth over the cloth covering the letters, applying firm, even pressure. Continue rubbing the iron on the cloth for two minutes.
Set the iron aside and try to peel the letters off the shirt. If the letters do not come off easily, turn the shirt back inside out and repeat the process, applying heat for two more minutes. Repeat until the letters peel off.
Apply glue remover to the sticky areas on the shirt. Follow the instructions on the bottle to remove the glue residue.
Wash the shirt to remove the glue remover from the fabric. Use hot water and wash the shirt by itself to prevent the glue from adhering to other pieces of clothing.
Always use the iron in an area away from children and pets. Place the iron on a non-flammable surface, never on the shirt or anything flammable or it may cause a fire. Keep your hands away from the metal surfaces of the iron to prevent burns. Be very careful when handling the heated iron-on letters; the glue backing will be extremely hot.