How do I delete sites already added to a project?

Hi can someone help I took projects from an old server copied all the data fields and move them to a new server . My question is how do I delete the site lists in the projects so I can ad better site lists ? Please help

Right click, modify project, delete URL cache/delete URL target history.

Right click, show URLs, verified, highlight, delete all, submitted, delete all.

Import your new list, uncheck all search engines and hit Start.

right click->modify->delete target url cache.

Thanks alot