New to board, question

Hello,

I am trying to find the right place to ask architecture questions and issues with SharePoint.

If this is the right place, please let me know suggestions or where I can search for the following:

We are running SharePoint Online. I do not have O365 Admin rights. I had created the Vandelay Project examples, site columns and document content types. After "playing" with the project I deleted the site columns from the content types, tried to delete the content types but keep getting the message they are being used somewhere. I put a ticket in with our IT but they have been unable to delete these with their rights. I have renamed them with a "z_" and assigned them to a Deprecated group. 

Can someone suggest what to do? 

Thank you,

Carol