1) Remove the Start a Campaign link from your menu.
- Go to Settings > Menu > Edit Main Menu
- Click X next to Start a Campaign
2) Remove the links from anywhere in your theme files.
- Go to Settings > Themes > Edit Active Theme
Usually these are in the Campaign, Campaigns, Project, and Place templates.
3) Double check that your sponsorship types do not let people set up personal fundraising campaigns.
4) Hide the "Your Campaigns" section of the supporter portal: http://support.reachapp.co/knowledgebase/articles/1939558-how-can-we-hide-the-your-campaigns-section