Delete line without adding to clipboard?

Ctrl-L deletes current line; I use this constantly.

Unfortunately, it also replaces the text that I have already copied. Is there another shortcut to delete an entire line, but not add the contents to my clipboard?

Ctrl + Shift + L

You can swap this around in Macro - Modify Shortcut/Delete Macro - Scintilla commands, and then around line 90, there's ones for SCI_LINECUT and SCI_LINEDELETE

By default Ctrl + Shift + L however you can change it to something like Shift + Del by going to the Settings menu, Shortcut Mapper, click on the Scintilla commands tab, scroll to command 90, "SCI_LINEDELETE" and adjust the shortcut from there. Valid as of Notepad++ 6.9.1. If it changes comment and I'll update my answer. You'd think people would answer with how to change a shortcut in a customizable editor?

Ctrl + Shift + Backspace deletes to the start of the line, and Ctrl + Shift + Delete deletes to the end of the line. So you could press both in quick succession. Or Home/End and one of the combos.