Hi!
Just figured it out myself, so here it is:
1. Go to: C:\Users\*your name\AppData\Roaming\Cakewalk\ACT Data
2. Delete everything that seem revelant to what you want to reset, for the eq, maybe the prochannel ACT file will do it.
3. Once deleted, press and hold the "SHIFT" key on your keyboard and launch Sonar, Sonar will then rebuilt its default files.
Worked for me, hope it will do the trick for you :)