How do you dull a knife blade without special tools?

I just bought a new butterfly knife (Kimura 6) with a VERY sharp blade, and I need to make its blade dull (as dull as a butter knife if possible). I will never use it for any cutting task and I only want to flip it around, so I don’t want any sharpness.

How can I do this without any special tools? Does a brick (or slab of rock) work?

Thanks in advance!