To add, remove or view a plan item attachment while you are in Edit mode, you can follow the steps below:
Should you wish to know more about adding or editing a plan item, you can visit this link.
Simply double-click on the plan item to open its details and either select Delete Attachment or View Attachment from the options provided.
Pro tip: To display the plan item attachments in the plan editor while you are in view mode or in edit mode, make sure you select the Plan Item & Documents dropdown option on the top-left corner.