can you remove an blocked ip in aws WAF?

You can list the IPs blocked by the rate limiting using the commands listed here: https://docs.aws.amazon.com/waf/latest/developerguide/listing-managed-ips.html

You can't delete IPs blocked by a rate limiting rule but they will be removed automatically once the rate from this IP drops below what you have specified in your rule.

When the rule action triggers, AWS WAF applies the action to additional requests from the IP address until the request rate falls below the limit. It can take a minute or two for the action change to go into effect. - https://docs.aws.amazon.com/waf/latest/developerguide/waf-rule-statement-type-rate-based.html