can i bulk delete blocked number from iphone ios 17

It is one at a time. Blocking number typically has no impact on spammers that spoof the phone number and you may only receive a call from that number once. It is only useful when you receive repeated calls/messages from the same number.

For Spam Blocking, check with your cell provider as many have services that just need to be turned on that will block spam calls before they even get to your phone.