How can someone achieve GRE waiver? How can somebody get an admission in a graduate science/technology/engineering program US university without GRE?
At this level of generality, I think all one can say is the following:


Look for programs that do not have a GRE as part of their admission requirements.
For departments that do require it: if you have some specific reason for being unable to take the GRE, or for not having scores that meet their criteria, contact someone at the department and ask how to proceed.  (Admissions information normally includes the email address of a contact person.)  In many cases, you will include some explanation in your cover letter or statement of purpose.
If a department requires the GRE, and you don't have a compelling reason for not taking it, or for doing poorly: don't apply to that department.