Stoyan To remove your payment method you will have to login to Azure portal and use the left hand side menu to navigate to "Cost Management + Billing" section and click on the "Payment Methods" link to view the payment methods that you have already added to your account. You can edit or delete the methods for a subscription based on the details that are displayed on the screen.
You can choose to use Azure students subscription from this page by applying for the same. You will have $100 credit for student subscription and you will have to convert to pay as you go option if $100 limit is exhausted. See the FAQ page before applying for the same. Thanks!!
If this answers your query, do click Accept Answer
and Yes
for was this answer helpful. And, if you have any further query do let us know.