"Security was able to intervene and quell the situation."
“Romero made statements and exhibited actions, while intoxicated, that brought discredit upon the APD,” the disciplinary memo details.
Romero--who serves as the vice president of the Austin police union--resigned from his union post after he was suspended for 20 days and demoted from sergeant to corporal Friday.
In addition being suspended, Romero will be subject to evaluations by a substance abuse professional.
The memo reports Romero made "unwarranted physical contact" with a man and a woman at the party who are only identified by their initials.
"Romero was unhappy with decisions made by the venue staff, and he proceeded to curse and yell at them and fellow personnel,” interim Police Chief Brian Manley said in a written statement.
Romero has apologized since being demoted.
"My behavior last November was wrong,” Romero said in a statement to the American-Statesman.
"I immediately apologized to whom I offended and am grateful they have accepted my sincere apology. I accept full responsibility and the punishment that has been levied."
Officials for the Austin police union accepted Romero's resignation, saying it took complaints from fellow APD personnel seriously, although he'll be eligible to qualify for a promotion as a sergeant in two years if he chooses to retake the sergeant's promotional exam.
"The association takes very seriously the allegations and findings in the Austin Police Department internal affairs investigation that has now concluded," the memo says.
"Mr. Romero has accepted responsibility for his actions, and we thank him for his years of contribution to association members."
Reports have not yet surfaced on who will take Romero's place.
Romero's demotion will reportedly include detective duties.