Hi, I'm Robert and I'll be helping you with your financial software question.
Officially there is no way to do it.
There is a third party company that will do it for you for a few hundred dollars
What I might try is exporting the data to an iif file and then making a new company without multi currency and importing the iif file. But I don't know if it would work.
I did see the quickbooksrepairpro.com option. Is this a legitimate service repair provider? Have you used them before?