if they are ltf, keep them.
the credit bureau enquiries are already done and score seems to be already affected, so why close the cards when the damage is already done?
sometimes the score also gets affected if you close the cards.
sbi cashback might be a good card for general online use where no other discount is applied.
but you will not use it if other cards are offering 10%-15% flat discount. eg. even in online shopping: goibibo, mmt, yatra, cleartrip, zomato, swiggy, eazydiner, fk, amazon, bb, and all the apps that you can think of offer some heavy discounts on different bank cards which are a lot more than sbi cashback.
i myself saved 1000rs (on a spend of 3200, approx 30%) over the last 2 days on my devalued zomato rbl card and indusind (both ltf).
a word of caution: as you mentioned that you are new to credit cards, in that case if you think these cards are a reason that you have started spending more, then definitely close some of them, as beginners unknowingly start buying unnecessary things on credit and fall in the credit card trap.
tip: buy only those things on credit card that you would have anyway bought using cash/debit card/internetbanking.
if you really go ahead to close cards, I would suggest closing cobranded cards first, because your sbi card beats them (or at least equals) and many bank offers are not applied if the card is cobranded. keep at least 1 card with airport lounge access if you travel by air.