Once you merge two vendor names, you can't
Situations where you can't merge a vendor
You can't combine more than two 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.
Click the Vendor Center.
Click the Vendors tab.
Right-click the vendor name you don't want to use, and then click Edit Vendor.
In the Edit Vendor window, change the vendor name to the same name
as the vendor you're combining it with.
Click Yes to confirm that you want to merge the two vendor names
under the same name.
Other ways to remove a vendor
What if a customer is also a vendor?
Changing information about (editing)