It got my attention simply because I was in the middle of dealing with the exact same issue from one of my projects. I have been told this is a known issue by Autodesk and it is fixable. However, it was going on for weeks to try to have their support team to resolve the issue.
So, what's the big deal, you might ask!? For some unknown reasons, these "rogue" family types starting to come up from nowhere and it created many types of tick mark, dimension style and text style on its own. All of a sudden, you have these non-company standard styles in your file, it really becomes an annoying issue.
From the same thread, people have responded with a few solution. Some said to use #dynamoBIM like John Pierson or using a 3rd party solution like Ideate explorer. **(For the record, I have not tried these yet as of the published post)
Out of my curiosity, I thought this could also be done using Revit Lookup.
I was introduced to Revit Lookup by my previous colleague like a year ago. Initially it was for me to understand how Revit organizes each group/type of elements under the hood.
To troubleshoot the issue, I first place a "rogue" type of dimension in a view (it can be any view including drafting view). Select the dimension (or the element), go to Revit lookup and choose Snoop Current Selection.
It reported a list of information associated with this element, it looks something like this...
2 items are important to know:
Id - which is the Revit element ID (Instance)
GetTypeId - which is the Revit family type element (Type)
Usually, it is the type ID that is "under the hood" so user would not normally get to it.
Now that I identify the type ID for this rogue dim style, I can use Select elements by ID from Manager tab
Type the type ID number in the field, once it is selected, hit Delete! It prompts me with a warning, hit OK.
Like I mentioned above, there are more than one way to resolve this issue, I thought this might offer a different approach.
You can learn more about Revit Lookup from this site to download the tool for yourself and it is free.
Revit Lookup Builds from 2015 -2019