Once you merge 2 vendor names, you can't reverse it. More ...
All transactions, even in closed periods, will be under a single name
Merging vendors may affect previous financial reports
QuickBooks removes the data associated with the merged vendor, such as address and phone number
Situations where you can't merge a vendor
You can't combine more than 2 names at a time.
You can't merge a vendor name with a name from a different list, such as merging a vendor with a customer.
Choose Vendors > Vendor Center.
On the Vendors tab, double-click the vendor you don't want to use.
In the Edit Vendor window, change the vendor name to the same name as the vendor you want to combine it with.
Click Yes to confirm that you want to merge the 2 vendors under the same name.
Other ways to remove a vendor
What if a customer is also a vendor?
Edit a vendor