ANSWER:
It is not possible to turn off Quote Metrics calculation as it is part of Zuora Quote Managed Package code. . However, you can hide quote metrics Section from the Quote Detail page by going to Zuora Config > Layout Configuration Settings. Select the "Quote" for Object Name, "Detail" for View Type, and "Default" for Record Type. Remove the zqu__Quote_Detail_Metrics: Quote Metrics from the Select Fields Sets box. Save your changes.
When you now launch the Quote Detail page, the Quote Metrics section will not display anymore.
BEFORE:
AFTER:
