so how do i roll back direct x?

i'd recommend you use the switch '-dxlevel xx' in the startup options.

i.e if you want DX level 9.0, use '-dxlevel90'

startup options?

Yep.

Right click the game in steam>properties>launch options...

You can do the same with non-steam games/apps too by editting the shortcut details. ie, add the switch to the end of the file path in the shortcut's properties.