You can remove references from any of your custom groups or online search groups. The references will still be in your library and appear under All References—they just will not appear in that particular custom group.
To remove references from a custom group:
In the left Groups panel of the library window, click on the name of the group.
In the reference list, select the reference(s) you want to remove. You can select multiple references:
Hold down the Shift key and click on two references to select a range of contiguous references.
Hold down the Control Ctrl key and click on individual references to select them.
Select the Remove References from Group command in one of these ways:
Press the Delete key on your keyboard.
From the Groups menu, select Remove References from Group.
Remember that the selected references are only removed from this group. They still exist in All References and possibly in other groups.
If you really want to delete the references from your library, see Deleting References from a Group.
Warning: When you delete a record from a smart group, EndNote also deletes the record from All References without warning. To restore the reference, go to Trash, and then right-click to bring up a menu. Select Restore to Library and EndNote returns the reference to the smart group.