Whether you've decided to move on from EndNote to another reference manager, or you are sending references to a colleague using a different tool, the export function built into EndNote is there to help. EndNote can export references as four different formats:
Text file (.txt)
Rich text (.rtf)
Most other reference managers will be able to import references from at least one of these formats. Prior to selecting the format, ensure that file is compatible with the other reference manager you are exporting to.
Select the reference(s) you wish to export.
On the menu bar, click File -> Export...
Navigate to where you would like to save the file. Name it, and select the file type to save it as. Output style is your own personal preference, but to ensure all information is transferred, consider selecting Show All Fields.
Ensure Export Selected References is checked off, unless you are exporting your entire library.