The following command reports the number of files in the 2006 directory, including files in all subdirectories:

find 2006 -type f | wc -l

The following command deletes all the files in the 2006 directory, including files in all subdirectories:

find 2006 -type f | xargs rm

When both commands are in your bash history (left over from when you moved the 2005 directory), you should probably be careful before hastily executing one.