Remove Callout
To remove a diffuser callout, go to
Ribbon: 
Remove Callout
Pulldown Menu:
You will be prompted to select the diffuser callout to be removed. You can also select the diffuser itself.
Select diffuser callout to remove:
The diffuser callout will be removed.
Related Options
Diffuser callout insertion: Sets whether a diffuser callout is inserted along with the diffuser.