I found this post when searching for a solution to the same question. However, when I try to save the vendor file without a Social or EIN, an error message prevents me from saving the file as that is a required field. Please help?
You can only send an email invitation during the initial set up in QuickBooks.
You'll need to update the email address from their profile. However, you can't re-invite them to complete their W-9 information. You can add them again as a new contractor and make the other one inactive.
Here's how:
From the left menu, click Workers.
Select the Contractor.
Locate the contractor, then click the drop-down under their name, then hit Mark as inactive.
Additionally, if you have a transaction to that contractor, you'll want to reallocate those transactions before inactivating it.