As it becomes easier to create AMIs, you may find you end up with more than you need!
AMIs are made up of EC2 snapshots, which are stored in S3. There is a cost associated with storing snapshots, so you will want to clean them up periodically. Given the size of most AMIs (usually a few GBs), it is unlikely to be one of your major costs.
An even greater cost is the administrative overhead of managing too many AMIs. As your images improve and fixes are applied (especially security fixes), you may want to prevent people from using them.
To remove an AMI, you must first deregister it, and then remove the underlying snapshots.
Make sure you do not deregister AMIs that are currently in use. For example, an auto scaling group ...
