How to change the location of user's download folder?
Delete the old folder and symlink the new download path to the old download path. Make sure to copy everything in the old download directory to the new directory

# set newdir to the new directory
NEWDIR=/path/to/new/download/path
# This path can also be relative to the user path (~/relative/to/user/path)

# copy all files in old directory to new directory
find "~/Downloads" -type f -exec cp {} "$NEWDIR"/ \;

# delete folder and contents in the default path
rm -rf -v ~/Downloads/

# symlink new path to old path
ln -s "$NEWDIR"/ ~/Downloads