The svn:ignore is only for files that are not already in the Subversion repository. This folder already is.
You can use the svn update --set-depth exclude folderName to remove this folder from your working directory:
$ svn update --set-depth exclude bigFolder #Removes "bigFolder" from workdir
D bigFolder
$
Next time you do an update, bigFolder won’t show up in your working directory. If you want it back, you’ll have to reset the depth:
$ svn update --set-depth infinity
U bigFolder
U bigFolder/File1
U bigFolder/File2
...