SEAL BEACH, Calif. (KABC) -- A school principal in Orange County was under scrutiny Thursday for her response to Nike's controversial ad featuring former San Francisco 49ers quarterback Colin Kaepernick."Believe in something -- even if it means sacrificing everything," Kaepernick says in a commercial marking the 30th anniversary the sports apparel company's legendary "Just Do It" campaign.The two-minute spot is scheduled to make its television premiere Thursday evening during the NFL's regular-season opener. The new ad campaign featuring Kaepernick has prompted calls by some for a boycott of Nike.Some people have taken to social media with vows to burn or otherwise discard their shoes or clothing that bears the brand's iconic swoosh. Among them was the principal at J.H. McGaugh Elementary School in Seal Beach.A Facebook post published by Roni Burns-Ellis read: "My newest rag! When Nike signs an anti-American thug to represent their brand, I will not support, wear, purchase, or endorse their product."Bye-bye Nike," she added.The post has since been removed. But many people took issue with her use of the word thug and that she's in a public position.More than 400 people have signed a petition on the website change.org expressing concern and demanding that leaders of the Los Alamitos Unified School District act civilly.But other parents defended her."I agree with her. Everything she's done. I mean Colin Kaepernick, he's disrespected the military, disrespected this nation just by kneeling during the anthem. You don't do that. That's disrespectful," parent William Haughland.Burns-Ellis offered an apology Thursday afternoon, saying she never meant to offend anyone and regretted using the word thug. The district also issued its own response."We need to always be conscientious about approaching differences in a respectful manner and about the use and impact of social media," Superintendent Sherry Kropp said in a statement to ABC7. "I understand that what someone writes publicly does reflect on us and can damage the good work we are doing. We care deeply about all students and want them to thrive in a diverse society."