I tried to install ADDTHISS social networks extension, on first attempt it installed successfully but it was not working properly so I tried re-installing. Now if I try installation, I am getting this error:
./app/code/community/AddThis/SharingTool/Block/Share.php' already exists
and ADMIN panel and Website shows ERROR 503, Error 503 was maintenance.flag and I can get website back. How should I remove this extension completely so that I can reinstall it again.