A Link can be removed from the current Revit project by selecting the Link Name in the main dialog and either pick the Delete key on your keyboard or right-click to select the Delete option.
You may also use Shift+Select to select multiple links for deletion.
Deleting a link definition does not alter the Revit project data structure in any way.
Tip: If you think you might want to use the link in another project, save the link definition to file. For more information, see Saving Links and Loading Links.