qmv lets you use an editor - 2 columns - left is original name, right is the new name. If you are excellent with your editor of choice, this would be 10 seconds.
rename is a perl CLI tool. The regex matching would be funky for someone not used to perlre. There's a manpage about it (man perlre). Also, if the directories are all at the same level in the directory structure, that would make life a little easier. What should happen if the target (new name) already exists? That's a pretty big failure mode for any batch tool.
Code:
$ rename 's#\[1\]$##g' bash-file-globbing-pattern
With rename, the first character after the 's' is the regex separator. Often you'll see this as '/', but that can be confusing when other characters need to be escaped. Another often-used alternate regex separator is '|'. That's pretty safe. Metacharacters need to be escaped if you want them NOT to be used for the perlre meaning.
Or you could just create a list of all the directories you want using find - save that to a file. Then create a mv script from that list. That would have the most hands on - effectively doing what qmv does, just with more assurance.
Code:
mv 'old_name[1]' old_name
mv 'really-old-name[1]' really-old-name
...
I've used this to rename hundreds of files before someone here recommended qmv. 
qmv changed my life.
I'd use qmv with vim as my editor, but vim can do columnar edits freakishly fast once you know how-to do it.
Adv Reply
Bookmarks