Removing Racial Restrictions?

[MardukBathory]

How do I remove racial restrictions from sub-classes like BladeSinger?

I had it sussed before, but with the latest updates I had to do it again, only to realise I had forgotten how. I thought I had it, and deleted the 'Expr-req' "You must be an elf or half-elf to become a Bladesinger" but suddenly every change I made to my goblin bladesinger came with an error message.

THEN I decided to add a level of artificer, but changed my mind the following morning and decided to add another level of wizard, instead, but then I got a succession of SEVERAL DOZEN error messages I had to click my way through before one big one, and then Hero Lab Crashes.

I have even tried uninstalling and reinstalling hero lab. (It's fine if I make an Elf BladeSinger, btw, but whenever I try to make those changes to my goblin it happens again).

(I did actually try looking it up, before, but I couldn't find what I was after).

I should have asked here sooner. I am a giant idiot. What should I have do to remove the restriction that I should have done before?