You can remove either type of wall, but if the wall is load bearing, you have to take special precautions to support the structure during removal, and to add a beam or other form of support in its place.
No matter how careful you are when removing drywall from a wall or ceiling, it will never be in “as new” condition. You may be able salvage it for reuse, however, if you are systematic in your approach, and your success will depend on how it is attached and whether it has been taped.
Look at the Floor Joists. If you can see the floor joists, either from the basement looking up to the first floor, or from the attic looking down to the floor below, note their direction. A load-bearing wall will often be perpendicular
to floor joists.
You should not need to apply for planning permission for internal alterations including building or removing an internal wall. If you live in a listed building, however, you will need listed building consent for any significant works whetherinternal or external.