Before returning to an earlier variation, check to see if you still have this program conveniently offered. This assumes you were using CC2015.5.1 otherwise change the path to whatever Photoshop version you had.
' C: \ Program Records \ Adobe \ Adobe Photoshop CC 2015.5 \ Plug-ins'.
If you made use of the default setups on establishing CC2017 it will certainly have uninstalled your previous variation of Photoshop, nevertheless normally it will certainly leave the 3rd party folder alone. If there are papers in the old plugin folder duplicate them to.
C: \ Program Information \ Adobe \ Adobe Photoshop CC 2017 \ Plug-ins.
There is usually no demand to run installers once again. Hope it assists you.