Reverting to specific build

[Bhasky]

Model Name: 6z
Firmware Version: 171
Rooted or not: not
Frequency of Occurrence: NA
APP Name & APP Version : NA
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Safe way to get back to specific build from 10 - 9 ?
The one provided by ASUS reverts to 194.
I searched fastboot image for FIRST BUILD of ASUS 6Z , but couldn't find it.
I never installed any third party apps or never rooted my phone and I don't want, so asking for safe/official ways

[ARP_ASUS]

Hi @Bhasky
Not all specific versions will support downgrade. Yes, the one provided on site will revert to.194 and is available right now. Do let me know if any further concerns.