You can choose to disable third party cookies only. You can find the description of how to delete these cookies in Firefox here: https://support.mozilla.org/en-US/kb/disable-third-party-cookies . If you use another Internet browser please use the help function of your browser to find out how you can amend these settings.
For opting out the individual partners you can click on the IAB optout page: http://www.youronlinechoices.com/uk/your-ad-choices or click on the Ad-Choices icon in or near the ad.
If you select to opt out of advertising, you will still see ads, but they may not be as relevant to you. If you delete your browser cookies or if you use a different computer or different browser and want to continue to be opted out of interest-based advertising, you will need to opt out again.