I'm currently using JIRA next-gen projects in an instance of JIRA Cloud.
I've created Epics, which have created a Roadmap and Board, but since then, some of my Epics have needed to be placed in Cancelled status.
I don't need to see them on the Roadmap or Board any longer, but certainly do want to deleted them.
Each Epic has several tasks. I've changed those statuses to Cancelled as well.