Hmm ... nice
In my machine if I open Firefox it opens waterfox
As I set it as the default browser.
I hope an uninstallation of Firefox (that one in program files x86) will be enough
For a 64 bit system, waterfox is the best, and you dont need the 32 bit version anymore, actually .
Let us know what is the situation after the uninstallation.
Edit : In that case, uninstall the both, and reinstall waterfox only .