@Arc, wow I really thought that was it haha, unfortunately it didn't help. I went to outlook mail, folders, and deleted items. ACCORDING to your screenshot you have a outlook.com calendar, not sure how you did because I don't have it. I only have things that I deleted manually myself which was just junk mail and random things. However i followed your steps anyway, and cleared cookies don't see how this affects the app itself but I did it anyway.
However this didn't still not solve my problem sadly..
For those who are wondering what my calendar currently looks like right now, I created a bunch of "secondary calendars" and none of them can now get deleted its like permanent now, i've also blacked out a couple calendars because those are the ones i actulaly use and need so i blacked it, everything else was for testing purposes but now I cant even delete them..