How do i switch off an existing client CIS off

Hello there, @user29818.

Good to see you here in the Community, I can help guide you on how to switch off an existing client from CIS in QuickBooks Online (QBO). 

To do this, please follow the steps below:

1. In the left tab menu, go to Sales.
2. Select Customers.
3. Look and select your client's name.
4. Click Edit.
5. On your client's information, make sure the Is CIS contractor box is uncheck. 
6. Select Save to apply the changes.

For additional reference, you can always visit these related articles below:

• CIS in QuickBooks.
• Already using CIS in QuickBooks?.

This will get you on the right track. Fill me in if you have any other concerns about the CIS in QBO. I'll be around to help. Wishing you and your business continued success.