Learning the flicking technique (removing the sugar) for your underarm is the main obstacle. To remove the Sugar, just like any other area of your body, you have to flick towards the direction of the hair. Although, for your underarm, this means flicking upwards- hitting your lower arm.
To go around this problem, some customers and employees have asked a friend, partner, or family member to help them during their first few sugarings until they are able to learn.
If you're still learning, try the technique described in this tutorial above. Although it will take a few more passes, you will be able to Sugar solo until you're able to learn the quicker/proper flicking direction.
Check-out our blog titled "Tips for Sugaring your Underarm." to see the two techniques back to back.