Thanks for your feedback! You disable on a particular site, by simply clicking the ABP icon and then click "Enabled for this site". You can also still disable Adblock Plus everywhere by clicking on the Firefox hamburger icon ( three horizontal lines in the upper right corner) >clicking on Add ons> click on Adblock plus> and choose disable from there. I hope this helps! Feel free to reach out if you have anymore questions via support@adblockplus.org.
