The exectuive has said he holds "different views on how to position and develop the company," thereby leading to a "common decision to separate our paths."
Interwetten hired Beier as speaker of the board in December 2018, when he was just 27.
He went on to state his intentions to Gambling Insider, suggesting Bwin and Tipico should be looking to replicate Interwetten and not the other way around.
The operator duly went on to report its best-ever financial year in 2019.
Beier said in an email sent to Gambling Insider: "Herewith I would like to thank all of you for the great cooperation over the past years.
"Interwetten is a very unique company, which is known as a loyal, professional and fair partner for 30 years.
"Interwetten is definitely ready for the future, economically healthy and highly competitive.
"Therefore I am very sure that Interwetten, together with all employees and valued partners, will further write its success story."