Raise a closure request, or ask them to transfer call to retention (mostly they won't available, so they take the request), then wait for their call (try to pick and do not reject) and ask them to any lower variant or threat for closure.
If not received call, you can always re-activate and continue use the card as usual and try after one week.
Its possible, got downgraded to smart but that also useless, so not sure what to do. EMT not possible, btw that you need to apply separately.
Platinum, Rewards equally waste, no use for them.
------------------------------------
Alternative way, apply another card (normally, not sure they fixed that 1rs. method if not its full process otherwise easy method), then close this card.
SC uses single account for all cards in CIBIL, so no changes in that department and also limit stays same.
--------------------------------------
I'll close the card by December and done with SC, its not working for me.