I mostly use yaourt instead of pacman to make my life easier when installing AUR packages. But they have the same syntax for this specific task.
Remove a package along with its installed dependencies
$ yaourt -Rcs <package>
cclean all these (.pacnew, .pacsave and .pacorig) files
sRemove each target specified including all of their dependencies, provided that (A) they are not required by other packages; and (B) they were not explicitly installed by the user.