Very simple browse to your /boot directory
It does make more sense to extract the image in its own directory eg "initramfs-blabla-dir" as it will literally extract directly to the pwd.
cp initramfs.img someotherdir
cd someotherdir
zcat initramfs-3.10.0-514.el7.x86_64.img | cpio -idmv
extract, contents, initramfs, gzip, dvery, browse, directory, eg, quot, blabla, dir, pwd, cp, img, someotherdir, zcat, _, cpio, idmv,