I would like to change home currency after turn on Multicurrency

Thanks for posting in the Community, @mumuko-zin-ansei. 

We want to ensure your multicurrency transactions are intact and accurate in QuickBooks Online (QBO). Thus, we're currently unable to change your home currency after turning on the said feature. 

I'd suggest deleting all your data and starting over from scratch to help achieve your goal.

If your QBO account is within 90 days of signup, here are the steps: 

1. Log into your QBO Company.
2. Change the URL to include /purgecompany. For example, edit https://sg.qbo.intuit.com/app/homepage to https://sg.qbo.intuit.com/app/purgecompany.
3. The next screen will provide a summary of the items to delete. Type YES to delete the data.
4. Click OK.

If your account is more than 90 days old, you can cancel it and create a new one. 

For your reference, check out this article: Can I Change My Home Currency?. 

Also, I recommend visiting these links to get answers to the frequently asked questions about using this feature in QBO. 

• Multi-currency FAQ
• Home Currency Adjustments

I'll be around to help if you need anything else. Keep safe.