A very easy one
Dan Donaldson
Just a place holder until a real one shows up 
Can you cross out the unnecessary letters to leave a common phrase?
ATCHEOUNMNE
MCESOSNAPRH
YRLEATTSEERS
Knowledge You Can Build On — Est. 1998
A very easy one
Dan Donaldson
Just a place holder until a real one shows up 
Can you cross out the unnecessary letters to leave a common phrase?
ATCHEOUNMNE
MCESOSNAPRH
YRLEATTSEERS
Re: A very easy one
Alex Y
That's easy:
ATCHEOUNMNE
MCESOSNAPRH
YRLEATTSEERS
That is most assuredly the answer, in one way or the other; the [very short] phrase you had in mind or the literal answer to the question: "Can you cross out the unnecessary letters to leave a common phrase?" 
But maybe someone else can. I kept getting stuck on the idea that it was going to be THE ____ LETTERS, but couldn't find anything down that path of inquiry.
Re: A very easy one
Larry Barrett
This is not much of an improvement on Alex's response, but might be the one you are looking for:
ATCHEOUNMNE
MCESOSNAPRH
YRLEATTSEERS
to both