Best to ask a doctor. You are or were on Dilantin? If you are what are your current levels? Who put you on Dilantin, if you are still on Dilantin, who maintains the prescription? 3.6 is well below the therapeutic range of 10 to 20 mcg/ml.
Nevertheless, a doctor would need to assess if the Dilantin can be discontinued and if so, what tapering dose to use. I take Dilantin twice a day. It's effective, and I've taken it for years.