As mentioned above you are always able to select an annotation within the panel to change its style, add a comment, delete it or add a link to it. Simply select the item, the viewer will automatically jump to the annotation and mark it. Then right click the annotation to open the options underneath.
In order to remove an annotations, regardless whether your have already saved it or not, select the annotation item in your panel, then either click the delete key on your keyboard or open the options listed in the right corner of the item and select "Delete".
Besides the option to delete an annotation, you are also able to edit it.
Furthermore, you can set a status for the item that for example reflects your review result. Here you can choose between accepted, rejected, cancelled, completed and none.
Once you selected the status, it will be listed directly underneath the annotation within the panel. You can always edit or delete the status.