sounds like you've finished the back
so Yes, cut yarn tail
ALWAYs leave 12 or so inches..
its easier to trim a too long tail, than to find you are an inch short!
later (in the part of patten labeled "finishing")you'll take those stitches on the holder, and put them back on a needle, and then make the finishing edge of the neck (ribbing, a collar, a hood, what ever)
after that, you've weave in the tail (and again easier to weave in 3 or 4 inches of 12 (and cut away the excess) than to try to weave in 3 inches!