how to remove old drum and replace with new drum.Do not see a relase lever to remove?

I would recommend you check the manual if you have not replaced drum before. But it is very simple. You remove the toner first. Drum tray will be left inside at this point. You now pull the drum tray out. There should be handle near the middle. Replace the old drum in same place. Make sure it sits all the way in at the bottom. Then you install the toner back