OSC to CPQ sync: Remove opportunity reference

Can the opportunity ID reference be removed in OSC when the opportunity ID is nullified at CPQ on a quote?

User creates a quote from Sales Cloud.

Based on specific selections, we are removing all the opportunity reference attributes in CPQ. But the quotes are still showing in OSC Opportunity» Quotes and Details tab.

Another question:

There is a field called SourcesystemReference. This field is not populated properly when creating the quote from OSC to CPQ.