I have applied EWS for RRB PO exam. if i am not able to show EWS certificate at time of certificate verification, will they cancel my candidature or they will consider it as general category ?
If you get the job based on your EWS rank and not by means of your General Category rank and if you have such rank that you will not get a chance to get job as an general candidate then your application will get cancelled.
Thus if your general rank isn't sufficient and if you get the call for verification through EWS then you have to submit EWS else your form will be cancelled.
I hope this answer helps. All the very best for your future endeavors!