Dear,
actually you can remove the old one but you don´t need.
Regarding the download, please go to the download location of your Steinberg Download Assistant and delete the version 1 file of Alto Glockenspiel.
Once you have done this and restart the Steinberg Downlaod Assistant, you should be able to download the new version.
Open the Steinberg Library Manager and check for version 2 of Alto Glockenspiel
Thanks
Frank