Here are the step-by-step instructions to remediate the issue of unused AWS EC2 Key Pairs using AWS CLI:

1. Open the AWS CLI on your local machine or EC2 instance.
2. Use the following command to list all the available key pairs:

aws ec2 describe-key-pairs

3. Identify the key pairs that are not in use and note down their key pair names.
4. Use the following command to delete the unused key pairs:

aws ec2 delete-key-pair --key-name <key-pair-name>

5. Replace <key-pair-name> with the actual name of the key pair you want to delete.
6. Repeat step 4 for all the unused key pairs.
7. Verify that the unused key pairs have been removed by running the command in step 2 again.

Note: Before deleting any key pair, make sure it is not being used by any running instances. If it is being used, first remove it from the instance and then delete it.

Sure, here are the step-by-step instructions to remediate the misconfiguration of unused AWS EC2 key pairs using Python:

1. Import the necessary libraries:

import boto3

2. Create a boto3 EC2 client:

ec2 = boto3.client('ec2')

3. Retrieve all the key pairs in the AWS account:

key_pairs = ec2.describe_key_pairs()

4. Loop through the key pairs and check if they are associated with any running instances:

for key_pair in key_pairs['KeyPairs']:
    key_name = key_pair['KeyName']
    instances = ec2.describe_instances(Filters=[{'Name': 'key-name', 'Values': [key_name]}])
    if len(instances['Reservations']) == 0:
        print('Deleting key pair:', key_name)
        ec2.delete_key_pair(KeyName=key_name)

5. The above code will delete all the unused key pairs in the AWS account.

Note: Please make sure to test the code in a non-production environment before running it in a production environment.