Is it possible?
Sure is. Are you renovating a home?
Could you post a picture(s) so we can see the details of your house & help you?
Check with a builder or architect to determine if the walls you want to eliminate are load-bearing or non load bearing. That will determine if the roof will collapse or not and how much extra it will cost to eliminate the wall.
Do you have Cathedral Ceilings or you would like them? If you are wanting to take out walls, do contact a Builder or Architect first as you could end up destroying your whole house if the right actions are not taken. You may well have to speak to Building Control at your local Planning department to see if they have would need to inspect or specify works...........Could be costly........!