One problem with fictitious genealogy -- as opposed to simple mistakes -- is that it keeps popping up. This is one reason we created a category for it:
If we could just make a fictitious person disappear from WikiTree, Murphy's Law says well-meaning people would re-create the profile again and again. So it's better to leave the profile, but with a clear indication that it's fictitious. It's best if the fictitious nature of the profile can be documented with sources proving it's fictitious.
Fictitious people cannot be born, marry, or have children, so they should be de-linked from all connections, and the fictitious connections noted in the narrative section of the profile.
A particular kind of fictitious person is a fraud, where the person was created by a fraudulent "genealogist" for money. Frauds also contaminate the profiles of real people, to whom the fraudster has given fake information and connections. These need to be documented, again, so that they don't keep reappearing. Gustave Anjou is now a well known fraudster, and the profile of any person that he ever wrote about needs to be categorized with "Gustave Anjou Fraud" as a warning to people that the profile may contain contaminated data if it is not thoroughly sourced with reliable data.
I looked at the two profiles you cited, and it is not obvious to the reader that it is fictitious or that anyone thinks it is fictitious. The profiles contain items that need to be removed, "this is my 27th great-grandfather" -- but one also contains a will or extract from one. Is the will fictitious, or is it just the connections that are fictitious. Both profiles are poorly sourced, so adding sourced information showing what is fictitious would be a big step forward.
If you have a source for the whole line of Pitt descendants being fictitious, it would be good to create a category "Category: Legendary Pitt Descendants" or "Category: Pitt Descendant Fraud" or whatever best describes the fiction, and then add the category to all the profiles impacted by it. That way, the information that is common to all the profiles impacted -- how the legend started, was it created deliberately, sources for more information about the legend or fiction, etc, can be put on the category page.
In addition, the profile manager is active on WikiTree this month, so some collaboration would be appropriate.