To leave a campaign, login to Causes.com, go to the campaign page, and click the gear icon under the campaign's name. Select the option, Leave This Campaign. This will remove you as a supporter and you will no longer receive email updates regarding this campaign.
If you do not see this option and are still receiving email communications, this means that you have taken one of the campaign's actions and are subscribed for email updates. You can edit your Causes email in your account settings.
Removing the campaign from your Facebook profile likes:
To remove the campaign's "like" from your Facebook profile, go to the campaign page and scroll over the Facebook like icon. Then click on the (x) that appears. This will unlike the campaign from your Facebook profile.