If you're editing from within an assessment:
Click on the item you wish to edit.
Click Edit and scroll down to view the item editor.
Skip the next step.
If you're editing from the item bank:
Click on the item you wish to edit, then click Edit in the top right corner of the popup window.
To view added standards:
click View Linked Standards.
To remove added standards:
Click View Linked Standards.
Hover over the standard you wish to remove, then click the trash can icon that appears to the right.
To add more standards:
Click Link to Standards.
Use the dropdown menus to select the standard you wish to link, then click Done.