To uninstall Apigee Developer Services portal (or simply, the portal) completely from your system, perform the steps described in Uninstalling Edge.
Alternatively, you can uninstall the following Developer Services portal components individually:
apigee-drupal
apigee-drupal-contrib
apigee-drupal-devportal
apigee-drush
apigee-php
For complete details, see Uninstalling Edge.