How to delete multiple blocked numbers on iPhone?

The iPhone has never had an option to bulk delete blocked contacts, but you can send a feature request here:

Feedback - iPhone - Apple

If you have a Mac, you can bulk delete the contacts at Mail > Settings > Junk Mail > Blocked, and it will be synced to any device using the same Apple Account. Currently that is the only way.

The Blocked Contacts feature is easy to use when blocking someone, but unnecessarily difficult to manage or reverse.

KEY PROBLEMS:

• No search for blocked contacts.

• Removing contacts is extremely slow; each deletion can freeze the interface for 5–15 seconds before another can be selected (or crashes).

• The Edit button offers no meaningful advantage over swiping left.

• Phone numbers and email addresses are combined into one long list, making navigation and cleanup even harder.

Managing blocked contacts should be as straightforward as adding them, but even after years of customer complaints and feedback they have yet to do anything about it.

(Although they do have a thorough and recently updated FAQ on how to easily Block Contacts)

auchaus wrote:

The Blocked Contacts feature is easy to use when blocking someone, but unnecessarily difficult to manage or reverse.

KEY PROBLEMS:

• No search for blocked contacts.

• Removing contacts is extremely slow; each deletion can freeze the interface for 5–15 seconds before another can be selected (or crashes).

• The Edit button offers no meaningful advantage over swiping left.

• Phone numbers and email addresses are combined into one long list, making navigation and cleanup even harder.

Managing blocked contacts should be as straightforward as adding them, but even after years of customer complaints and feedback they have yet to do anything about it.

(Although they do have a thorough and recently updated FAQ on how to easily Block Contacts)

You aren't speaking with anyone from Apple here. This is a user to user only forum, which Apple neither Participates, nor reads for user feedback.

While many may agree with you, you're sharing your what you think Apple needs to do with only other users.

Tell Apple what you'd like to see here --> Feedback - iPhone - Apple