I had selected EWS category during GATE registration , if I fail to submit the EWS certificate will my admission/application gets cancelled during joining of college? If so if my admission gets cancelled how can I change the category in Gate 2021 application form?
As per your query, YES if you fail to submit your EWS category certificate your application won't be eligible for admission.
To change your category you can do it in the correction window which the organizing institute will open on 28th October to 13th November, with an extra fee.
Please check here all the information about GATE 2021: https://engineering.careers360.com/articles/gate-application-form-correction
Hope this helps..
Good Luck !!