To prevent users from clicking Rescan Barcode Items, you need to disable the AdminBarcodePickingOverride permission. Follow these steps:
Click Settings then Warehouse User Accounts.
Locate the user.
Click Actions and then choose Manage Roles.
In the Picking-Super role group, find AdminBarcodePickingOverride.
Uncheck the box and click Update.
You may need to log out and log back in for the changes to take effect.