how to pause icloud drive upload from PC?

I just started using iCloud Drive and installed the iCloud for Windows. Made the mistake of moving about 50GB of data at one go into the iCloud Drive and now realize that I cannot pause the upload.

When I try to sign-out of iCloud, it prompts me that the upload is not completed and if I continue with the sign-out, ALL DATA WILL BE DELETED FROM THE LOCAL COMPUTER!!

Please someone do tell me that there is a way to pause or stop the upload and STILL KEEP all my 50GB of data on my local Windows PC...