To search for directories called Index in or below the current directory, and then to delete these, you would use find like so:
find . -depth -name Index -type d -exec rm -r {} \;
This does a depth-first search for the specific directories you are interested in and invokes rm -r on each of them in turn. We need to do a depth-first search (with -depth) as we might otherwise remove directories that haven't yet been visited by find, which would generate errors.
Use -path '*/Contents/Index' in place of the -name test if you need the Index directory to be a child directory of a Contents directory.
Using the zsh shell, or the bash shell with its globstar shell option set, you may also be able to use
rm -r ./**/Index/
or
rm -r ./**/Contents/Index/
This would call rm -r with a list of pathnames of directories called Index (assuming all the parts of the directory path are non-hidden, and assuming you're ok with also deleting directories symbolically linked via the name Index, and assuming the list of matching pathnames is not thousands of entries long). The trailing slash ensures that only directories are affected.