An experienced carpenter, or qualified framing contractor may be able to determine whether any given wall or support is loadbearing or not, and whether it can be safely altered or removed. 
If a permit is required - as it generally will be - or if otherwise in doubt, it may be wise to consult with an engineer.
Partial images of sample drawings for some actual Loadbearing Wall Certification Projects are included below. 
Drawings may not be reproduced; And, they are only to be used for the project and site identified in the drawing set.