how to delete a line without putting them into yanking?

[Rokia]

sometimes when I copy text from other application. and I want to yank
them into some file. so I press ^X^F to open the file, but emacs give
me a default path which I dont want, so I press ^A to goto the head of
this line, and press ^K to delete it, you know,then, when I press ^Y
,what I got is the path string ,not what I really want to paste.

so, how to delete a line without putting them into yanking?

thanks a lot.