Need to keep your leads inactive? Use Pending Leads.
Typically, leads are in one of four statuses: open, won, lost, or canceled. It's possible to place a lead into a pending status, this is typically only done when importing many leads.
Pending leads are not assigned to a user. They're designed to fit the workflow of importing thousands of leads, then slowly 'thawing' smaller numbers of leads. Use the bulk edit tool to convert pending leads into open leads.
Once you use the bulk edit tool to open a collection of pending leads, you can also bulk edit the pipeline and stage of those Leads.