Write an article based on this "Moisten the crease with a special leather oil. Use a heat gun or blow dryer to soften the leather on the top of your shoe. Massage the leather until the crease disappears. Leave the shoe on a shoe tree as it cools."
Make sure to really saturate the wrinkle with the oil so the leather around it will become supple. The oil will help protect your shoe from damage when you apply heat to the leather. You can buy leather oil, such as mink oil or neatsfoot oil, at a specialty leather shop or wherever leather shoes are sold. Move the nozzle of the heat gun around, never staying in one place for more than 2-3 seconds. The whole process will probably take about a minute. Lighter leathers are susceptible to discoloration when they’re exposed to heat, so test a small area on the heel of the shoe before applying heat to more visible areas. The combination of oil and heat should make the leather pliable. Use your hands to stretch and smooth the crease until it starts to fade. Insert the shoe tree as tightly into the shoe as you can. As your shoe cools, the smooth texture will become permanent. Be sure not to tighten the shoe tree too much. Since the leather is hot, it will be prone to stretching.