On the OnZoom’s event creation or edit page go to the "Meeting Options" section and uncheck the Fundraising option to remove the fundraiser from your event page.
People will no longer be able to make donations, but any funds already processed will be forwarded to the organization that you designated.
If you change your mind, or want to donate to a different organization, just go to the "Donation Options" section and select the charitable organization that you'd like your attendees to donate to.