You don't actually need write access to a file/directory to delete it. You only need write access to the parent (removing or adding a file modifies the container, not the contained).
Remove write access to the parent directory, while keeping traversal and read rights, and you'll be sorted.
So don't put the stuff you want to protect this way in your home directory, but somewhere else, and symlink the relevant directories to your home directory.
Remove write access to the parent directory, while keeping traversal and read rights, and you'll be sorted.