Thanks for the helpful answers! I used them to solve the problem in a slightly different way:

Since the file is relatively new, I simply edited the first entries in the checking and savings accounts, and changed "Opening Balance Equity" to "Unrestricted Net Assets".

Then I deleted the useless "Opening Balance Equity" account, since there were no entries in it.

Then, since this non profit has never, and probably never will, receive restricted contributions, I renamed "Unrestricted Net Assets" to simply "Net Assets", which will undoubtedly avoid questions at the next board meeting.