Click on the Approval Settings tab on the right side of the page (as shown below). This will display the possible settings for the customer approval process of this sales quote template.
To switch off the ORDER NOW button, you simply need to untick the check box under to the label SHOW "ORDER NOW" BUTTON
After you untick this check box, click on the Save button.
All future sales quotes using this sales quote template will no longer show the ORDER NOW button. Please note, this configuration change will not affect any existing sales quotes sent to customers.