I am trying to get the right way to calculate the removal of EtG from alcohol intake from the body

You'll do better if you use Google to find this information.

As a rule we don't give out this information as it is generally used to cheat the EtG/EtS tests. As well only a general rule is available, 60-80 hours after alcohol consumption. There are factors that also change that number and those include:
* Previous alcohol consumption history. IE, were you previously a heavy, medium, light drinker.
* Genetic predispositions
* Biological issues
* previous consumption
* Other non-beverage consumptions, hand sanitizer, White Wine sauce, etc...
* Granularity of test.

An exact formula isn't available because of the above.

As well if you're in an agreement where you're forced into sobriety there are two paths that you can follow:
1). Refuse alcohol, all alcoholic beverages, food stuffs, and products. Stay sober and take the tests for the duration of the testing period. Low stress, a little less fun, but you can be the DD that has all the stories for the next morning.
2). Try to cheat a test that was created by people who are REALLY good at what they do. Take the chance of possibly failing and having bad things happen because of it. Be stressed out and nervous of every test you take.

The choice is yours.

Good luck.

There is no formula, like the rate of elimination of alcohol in BAC.

The "Right way" is don't drink at all while you are under prohibition and random testing.

http://www.burlingtonlabs.com/assets/Uploads/EtGroutine-use.pdf