Unable to delete uploads sub-folder and its contents under project wikis folder

I am sort of new to using Git and wikis under GitLab. But ever since I started using GitLab Wikis to document details of projects, I have been able to do away with cumbersome README txt files.

Recently, I came across a problem under my project’s list of Wikis where some links looked different and weird, and they could not be deleted.

Under my https://gitlab.com/anandksrao/pda_orthology project/ website:

example of a regular looking wiki link that I can edit, and add or remove file attachments : /wikis/Domain-Length-Variation


example of a link that opens a file attachment, but that I am unable to edit or delete:

I am also providing this same info as annotated screenshots.

So how can I delete these weird links and files?
And how do I make sure I do not accidentally create these again?
Finally, how do I know deleting them will not break hyperlinks to these files in other wikis?

Thanks, in advance, for your advice and help.