If there is no spline to remove you just need to gently pry it out or cut it carefully. If you are planning on trying to reuse it, shop around for new stock as the old stuff is probably hardened and not going to be easily reused. If it is still soft, warm it up and apply a little soapy water or iosproply alcohol for a lubricant and you might be lucky with a small flat tip screw driver or some picks to get it started. I suspect oncecyou get it going it will come out easily.