Delete Contact query

Hi all,

I have an issue with sharing a PowerBi report with external users. I used the manage permissions function and copy pasted a bunch of emails from our clients and it converted them into some kind of contact, but varied the email address to remove the @ and replace it with an _ so now understandably, it has not successfully shared the content with them. 

Further, now the function insists on remembering these contacts as having this incorrect e-mail address, i have tried every possible method of manually entering in their correct email address and it just autocorrects to its recorded contact details for that person with the incorrect e-mail address and i'm not able to share the content with them. 

Is there a way to somehow get PowerBi to forget these people?

Many thanks in advance for your help.