I'm really stuck here...

Tried creating the workflow for Trailhead Module 2 "Create a flow to streamline entry of new accounts, contacts and opportunities".  Saved and made active, tried to test and got an unhelpful error message.  Now I cannot reopen the message to edit, and since its active I can't delete to start over either.  Error message on open is:

Thanks in advance for any help...

I'm really stuck here...

Tried creating the workflow for Trailhead Module 2 "Create a flow to streamline entry of new accounts, contacts and opportunities".  Saved and made active, tried to test and got an unhelpful error message.  Now I cannot reopen the message to edit, and since its active I can't delete to start over either.  Error message on open is:

Thanks in advance for any help...

This challenge seems simple enough but I'm stuck and any help would be appreciated. 

So the Challenge is Create a validation rule to check that a contact is in the zip code of its account. here is the question below:
To complete this challenge, add a validation rule which will block the insertion of a contact if the contact is related to an account and has a mailing postal code (which has the API Name MailingPostalCode) different from the account's shipping postal code (which has the API Name ShippingPostalCode).Name the validation rule 'Contact must be in Account ZIP Code'.
A contact with a MailingPostalCode that has an account and does not match the associated Account ShippingPostalCode should return with a validation error and not be inserted.
The validation rule should ONLY apply to contact records with an associated account. Contact records with no associated parent account (hint: you can use the ISBLANK function for this check) can be added with any MailingPostalCode value

Here is my  work.. Any help would be appreciated.. thanks, 

Rule Name Contact_must_be_in_Account_ZIP_Code Active [Checked]
Error Condition Formula AND( BillingPostalCode = ShippingPostalCode )
Error Message Billing zipcode does not match the Shipping Zipcode Error Location Billing Zip/Postal Code