This year we have moved all the schools to Assessment Builder Option from Fixed Assessment. However there will be few schools who will be requesting to opt out from the Assessment Builder and need the ready Fixed Asm's to save time in Question paper creation or other reasons.
How to move the school from ASM builder to Fixed ASM
Go to Nucleus and click on 3 hamburger Lines
Click on Admin Panel and then click on Assessment Configuration 
Click on Default Assessment Configuration drop down and chose accordingly.
Vice versa for Fixed to ASM builder
Ticket SOP:-
Also if you got a request to change the ASM builder configuration just get the confirmation from AA/CSM and then proceed with the changes in the nucleus.
While closing the ticket please mention the reason for changing the ASM type then send an email to the AA/CSM keeping Yathish Dhavala and Ayush Goswami in cc.
Please refer to the below FAQs for ASM builder
FAQS:- Link