Hi
rautchampak62Thank you for your asking. Are you Max Pro M1 ZB602KL? If so, the downgrade file on our website "MaxProM1_downgrade_to_9" will bring your device to WW-16.2017.1912.060. Please refer to the following steps below as Android 10 to Android 9 guide
1. Download "Version MaxProM1_downgrade_to_9" and then put the image file into the root directory of the MicroSD card.
https://www.asus.com/supportonly/ZenFone%20Max%20Pro(M1)(ZB602KL)/HelpDesk_BIOS/2. Insert MicroSD card into phone and then power off the device.
3. Long press with "Power" key and "Volume Down" key together and stop after feel the vibration to enter Recovery Mode
4. Use "Volume Down/Up" key and press "Power" key to choose "Apply update from external storage"
5. Select the downgrade file
6. When the updating process is done, Choose "Wipe data/factory reset" and tap"Yes" to perform the master clear.
7. "Wipe cache partition" > "Yes"
8. "Reboot system now"
#Android 10 to Android 9 Guide
https://www.asus.com/support/FAQ/1042349