Downgrading to Stock Rom using TWRP

[PJ7]

How did you get the stock zip?

From a site which has signed factory roms of YU phones taken from its official site.The official site doesn't have them now.They mirrored the official site roms.

[freshtyt]

You mean I will not be able flash it using twrp?Will I brick my phone if I do so?

there's only one way to find out the outcome by testing it yourself, that is if you are willing to risk a brick
better you use the other alternatives ie fastboot or twrp install image