Delete in txt file from a ruler in Notepad++

Hi Im not sure how to explain...

I have a txt file with loads of text but im only interseted on text from a particular area.

I want to delete all the text before this area

So If i could draw a ruler type line down the page of txt and then delete everything to left of it to leave with me text that im interested in ....

Hope that makes sense

CAn this be done in Notepad++

Mo