Can I set the Desktop sync client for Nextcloud to upload to Nextcloud only? Now, if you delete the file of the synchronization source (Windows), the file on Nextcloud will be downloaded. I want to stop downloading from Nextcloud even if I delete the sync source file.
Short answer: No. It’s not the right tool for the job.
First of all, try to see Nextcloud as the synchornisation source. if you think about it like that, It makes it easier to wrap your head around how it actually works. But something is still strange here, beacuse if you delete a file either on your Windows client or on your Nextcloud server it should also get deleted on the “other side”.
Sounds to me that you want to use your Nextcloud as kind of a backup target for files that you have on your computer. This is not the primary usecase the developers had in mind when they developed Nextcloud, but it can of course be used for that. However, as I already said, the Nextcloud Desktop Client is not the right tool for the job. But, you can of course use any backup / one-way synchronization tool for that purpose, that supports WebDAV as a storage backend. Unfortunately I can’t give you a recommendation for a specific product, because I don’t have this usecase myself and because I’m mainly using Linux.