I do not have access to SharePoint Powershell, but am (poorly) trying to develop in SharePoint Designer 2013. As I try to build a workflow, I've noticed several artifacts being stored that I cannot seem to delete, both in the Custom Content Types and in Workflow Task Columns. My workflow has far, far fewer approval workflows than those show, which tells me these are all left-overs from previous attempts that I have since deleted from within my workflow. How do I delete these?
You have to do this series of tasks:
- Remove all items that use these content types
- Remove these content types from all lists
- Empty both Recycle bins
- Remove content types from site
You could use eg. SharePoint Manager which will tell you where these content types are used.