Deleting Sources from Your Zotero Library
If you want to delete one or more items from your Zotero library, select the item(s) in the center pane. Right-click (on a Windows computer) or control-click (on a Mac) over the highlighted item(s) in that same pane, and choose "Move Items to Trash."
When prompted for confirmation, click 'OK.' The items should disappear from your Zotero library.
If you change your mind, you can go back and restore the items from your trash.
You can delete your items permanently by right-clicking (or equivalent) on the 'Trash' folder in the left pane, and selecting 'Empty Trash.'
After doing so, you will not be able to restore these items.