Owner Paul Bryant said the school was taking a stand to help women not become victims.
Attacks on women were terrifying and potentially life-changing, he said. But with the right knowledge and basic skills, women could escape and help others.
"Given the proper personal safety and self-defence training, a woman can break through her 'initial shock', utilise her adrenal rush and the skills she had learned to improve her odds of escape."
In Wanganui, Mr Leathem has taken a break from running self-defence courses for women because of a lack of interest.
Learning self-defence techniques was important in keeping yourself safe, he said. "You're learning how to get out of a hold, how to throw a punch, how to hit someone with an elbow."
Women also learned how to deal with knife attacks, and "what not to do".
"Going for a jog at night time, wearing earphones - you've got no idea what's going on around you."
Mr Leathem hoped to get the $30 four-week courses running again soon.
While devices like pepper spray and tasers are outlawed in New Zealand for personal use, some self-defence instructors encourage women to use perfumes and aerosols - which can have a similarly painful effect - in their place.
Coalition for the Safety of Women and Children spokeswoman Leonie Morris said self-defence classes were just one tool in the fight against violence towards women. The biggest problem was a culture which perpetuated sexist and outdated ideas about women.
She said more Government support for programmes to educate Kiwis about misogynistic attitudes was needed.