I know you really don’t want to throw up but sometimes we just know if we do it and get it over with, we will feel much better. It’s quite easy but a bit unpleasant. Head for the toilet bowl and kneel over it. Stick your index and middle finger down your throat. Get ready to gag and eventually throw up. Have fun.
Most people will use their gag reflex to make themselves throw up, see here for details. This can be done with your finger or a utensil to hit the gag point in your throat. In ancient Rome, they had ones carved from ivory to make themselves throw up so they could eat more. Not a healthy thing to do.